Unusable traceback during heat resource_type_show

[Sergey Kraynev]

If you have resource which references in environment file on not existing template you will get unrecognized error.
How to reproduce:
- delete or move file AWS_CloudWatch_Alarm.yaml from /etc/heat/templates/
- try to execute command:
heat resource-type-show AWS::CloudWatch::Alarm
or
heat resource-type-template AWS::CloudWatch::Alarm

you will get error:

ERROR: type object 'TemplateResource' has no attribute 'properties_schema'
Traceback (most recent call last):

  File "/usr/local/lib/python2.7/dist-packages/oslo/messaging/rpc/dispatcher.py", line 134, in _dispatch_and_reply
    incoming.message))

  File "/usr/local/lib/python2.7/dist-packages/oslo/messaging/rpc/dispatcher.py", line 177, in _dispatch
    return self._do_dispatch(endpoint, method, ctxt, args)

  File "/usr/local/lib/python2.7/dist-packages/oslo/messaging/rpc/dispatcher.py", line 123, in _do_dispatch
    result = getattr(endpoint, method)(ctxt, **new_args)

  File "/usr/local/lib/python2.7/dist-packages/osprofiler/profiler.py", line 105, in wrapper
    return f(*args, **kwargs)

  File "/opt/stack/heat/heat/engine/service.py", line 1004, in generate_template
    type_name).resource_to_template(type_name)

  File "/opt/stack/heat/heat/engine/resource.py", line 1082, in resource_to_template
    schema = cls.properties_schema

AttributeError: type object 'TemplateResource' has no attribute 'properties_schema'

I think we should wrap it in some understandable error message.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/135924

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/135924
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=51390e8ba70cc22202e27f972455af66d3dbe779
Submitter: Jenkins
Branch: master

commit 51390e8ba70cc22202e27f972455af66d3dbe779
Author: Sergey Kraynev <email address hidden>
Date: Mon Nov 24 08:04:12 2014 -0500

    Handle error with non existing template file

    This patch allows to propagate IOError instead of returning
    TemplateResource which does not contain property_schema.
    Change-Id: Ib1e09de8c10672312eea09f62a28f0885d98b089
    Closes-Bug: #1394552

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/140315

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/140315
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=a2a41b585b5aebaeedac5dcc5604686b7eec4ce0
Submitter: Jenkins
Branch: master

commit a2a41b585b5aebaeedac5dcc5604686b7eec4ce0
Author: Sergey Kraynev <email address hidden>
Date: Mon Nov 24 08:04:12 2014 -0500

    Handle error with non existing template file

    This patch allows to propagate IOError instead of returning
    TemplateResource which does not contain property_schema.
    It's the second attempt to adopt fix introduced here:
    Ib1e09de8c10672312eea09f62a28f0885d98b089.

    Change-Id: I45604648e3078f8ec6ba8b87a1c08eb6fca790ae
    Closes-Bug: #1394552