Rename workers to api_workers and simplify code

Refactor a few ugly aspects of the multiple API worker patch to make
way for multiple rpc workers.  This came up as I was trying to add
multiple RPC workers using similar patterns and remembering that some
things were left in a rather awkward state.

Change-Id: I549db67af4af6a2df80e12cf233109dda5213c47
Imported Translations from Transifex

Change-Id: I585e3df5504fcc071811e0ec9f925bc493584b2f
Do not assume order of report list elements

This fixes the test_report_multiple_services unit test that breaks with a
randomized PYTHONHASHSEED (see the bug report).

The test assumed that the report list from self.driver.report_status() had
elements in a particular order. Found with PYTHONHASHSEED=2455351445.

The fix refactors the test case to handle an unsorted report list by
sorting it before checking equality.

Partial-bug: #1348818

Note: There are several other unrelated unit tests that also break with a
randomized PYTHONHASHSEED, but they are not addressed here. They will be
addressed in separate patches.

Change-Id: I542c3818821fa2f6e460fd254a3842530ecea8d9
Merge "Do not assume order of report list elements"
Merge "Rename workers to api_workers and simplify code"
Merge branch 'master' of https://github.com/openstack/quantum