Catch muranoclient errors at Packages panel

Handle CommunicationError, Unauthorized and Forbidden muranoclient
exceptions using special `api.handled_exceptions` context manager. It
has protection sending several duplicate horizon error messages during
processing of one request. Also catch errors in AppCatalog panel.

Change-Id: I8a9c5de66f25c65e7676801564c7ee38a27778d8
Closes-Bug: #1307451
Merge "Catch muranoclient errors at Packages panel"