fixes #6913 / BZ 1092143 - content view version - disable promote/remove on failed task

This commit will disable the promote/remove button for a content view version,
if the current task being executed resulted in in an error.  Once the error
has been resolved and the task completes, the buttons will be re-enabled.
Merge pull request #4523 from bbuckingham/issue-6913

fixes #6913 / BZ 1092143 - content view version - disable promote/remove on failed task