Refactor XXNotFound exceptions

[huangtianhua]

There are too many XXNotFound classes define in exception.py, refactor to one, such as:
class EntityNotFound(HeatException):
    msg_fmt = _("The %(entity)s (%(name)s) could not be found.")

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/187839

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/187843

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/187847

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/187890

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/187898

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/187839
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=0ba3206b401e761b37bc30c6917941c11b2b0bc3
Submitter: Jenkins
Branch: master

commit 0ba3206b401e761b37bc30c6917941c11b2b0bc3
Author: huangtianhua <email address hidden>
Date: Wed Jun 3 10:01:01 2015 +0800

    Use EntityNotFound instead of ImageNotFound

    There are too many **NotFound exception classes defined
    in exception.py. This patch will define a general notfound
    exception: EntityNotFound. And will use it instead of
    ImageNotFound exception.

    Change-Id: I2a09637be97905548b29673273e8579c69d42d52
    Closes-Bug: #1461343

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/187843
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=232fe4ae02fbad2ad57e925a76cb5323f6a452d1
Submitter: Jenkins
Branch: master

commit 232fe4ae02fbad2ad57e925a76cb5323f6a452d1
Author: huangtianhua <email address hidden>
Date: Wed Jun 3 10:20:19 2015 +0800

    Use EntityNotFound instead of ServerNotFound

    This patch will use EntityNotFound instead of
    ServerNotFound. And will remove ServerNotFound
    exception class definition.

    Change-Id: I5a5aba82d57056893d5d7e644448cbd3de632ea5
    Closes-Bug: #1461343

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/187847
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=96975c0a4b128eed3bd1cd7795b4a84c39d8f7d5
Submitter: Jenkins
Branch: master

commit 96975c0a4b128eed3bd1cd7795b4a84c39d8f7d5
Author: huangtianhua <email address hidden>
Date: Wed Jun 3 10:55:25 2015 +0800

    Use EntityNotFound instead of VolumeNotFound

    This patch will use EntityNotFound instead of
    VolumeNotFound. And will remove VolumeNotFound
    exception class definition.

    Change-Id: Ib56e5332a1409b94179679e1bf730dd438cc9d22
    Closes-Bug: #1461343

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/187890
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=6640b0580604b4365fda0854affe56198adb88c1
Submitter: Jenkins
Branch: master

commit 6640b0580604b4365fda0854affe56198adb88c1
Author: huangtianhua <email address hidden>
Date: Wed Jun 3 15:11:01 2015 +0800

    Use EntityNotFound instead of VolumeSnapshotNotFound/VolumeTypeNotFound

    This patch will use EntityNotFound instead of
    VolumeSnapshotNotFound and VolumeTypeNotFound.
    And will remove the two old exception class definition.

    Change-Id: I661c7b6b306da34f30c55914f74eebc6e8e16931
    Closes-Bug: #1461343

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/187898
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=2235165ab32ee0bce30545575d486d539ed85899
Submitter: Jenkins
Branch: master

commit 2235165ab32ee0bce30545575d486d539ed85899
Author: huangtianhua <email address hidden>
Date: Wed Jun 3 15:35:45 2015 +0800

    Use EntityNotFound instead of Keystone*NotFound

    This patch will use EntityNotFound instead of
    Keystone*NotFound. And will remove related
    exception class definition.

    Change-Id: I2b74a96edb84a250b6304b44533ff4ed435584fc
    Closes-Bug: #1461343

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/188248

[OpenStack Infra (hudson-openstack)]

Change abandoned by huangtianhua (<email address hidden>) on branch: master
Review: https://review.openstack.org/188248
Reason: Will separate to some small patches.

[OpenStack Infra (hudson-openstack)]

Change abandoned by huangtianhua (<email address hidden>) on branch: master
Review: https://review.openstack.org/188248