Bare SolumException raised in plan.py

[Ed Cranford]

https://github.com/stackforge/solum/blob/ced1c17502d45d1f1ab527c6a3cb05bf44bb8844/solum/api/controllers/v1/plan.py#L98

SolumException's own docstring (https://github.com/stackforge/solum/blob/ced1c17502d45d1f1ab527c6a3cb05bf44bb8844/solum/common/exception.py#L178) says to inherit from it and define msg_fmt

The line in plan.py above doesn't do that and in the event of our current delete race condition causes the actual exception to get swallowed by the msg_fmt problem.

The solution is to create a general database error exception there instead.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/145600

[Ed Cranford (ed--cranford)]

Manually trying to delete a plan with dependent assemblies ended up throwing a DBError instead of a DBReferenceError, so I changed the code to catch both kinds of exceptions and treat them both the same in that moment.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/145600
Committed: https://git.openstack.org/cgit/stackforge/solum/commit/?id=bde27ec5f1db09092981dcf79713028b5bcfbc14
Submitter: Jenkins
Branch: master

commit bde27ec5f1db09092981dcf79713028b5bcfbc14
Author: Ed Cranford <email address hidden>
Date: Mon Jan 5 15:09:36 2015 -0600

    Stop raising SolumException in controller/v1/plan

    Instead, raise a PlanStillReferenced exception.

    Closes-Bug: 1408400

    Change-Id: I9cf2dab3a678152d9408ecce235beeba3dc28383