Attempt to fix flaky AMO tests by not relying on ExtraAppTestCase anymore

ExtraAppTestCase causes problems depending on import order, because
any models with FKs that is imported get cached into its related
model's _meta._related_objects_cache.
Fixed errors on greek translation
Commit from Mozilla Verbatim by user shaohua.wen@gmail.com.: 4952 of 5481 strings translated (0 fuzzy).
Merge branch 'master' of ssh://github.com/mozilla/zamboni
Merge pull request #1287 from alexmiog/alexmiog_el

Fixed errors on greek translation
Merge branch 'master' of ssh://github.com/mozilla/zamboni
Commit from Mozilla Verbatim by user shaohua.wen@gmail.com.: 4954 of 5481 strings translated (0 fuzzy).
Commit from Mozilla Verbatim by user smolejv@gmx.net.: 1937 of 1937 strings translated (0 fuzzy).
Commit from Mozilla Verbatim by user shaohua.wen@gmail.com.: 4955 of 5481 strings translated (0 fuzzy).
Commit from Mozilla Verbatim by user shaohua.wen@gmail.com.: 4960 of 5481 strings translated (0 fuzzy).
Commit from Mozilla Verbatim by user shaohua.wen@gmail.com.: 4967 of 5481 strings translated (0 fuzzy).
Commit from Mozilla Verbatim by user marsf.: 1796 of 5452 strings translated (27 fuzzy).
Commit from Mozilla Verbatim by user marsf.: 1797 of 5452 strings translated (27 fuzzy).
Commit from Mozilla Verbatim by user shaohua.wen@gmail.com.: 4597 of 5088 strings translated (0 fuzzy).
a minor, but key, fix
fixed search merorizing version (bug 729414)
Merge pull request #1267 from diox/fix-flaky-tests

Attempt to fix flaky AMO tests by not relying on ExtraAppTestCase anymore
Merge pull request #1264 from vinyll/version_sidebar-729414

fixed search merorizing version (bug 729414)
Commit from Mozilla Verbatim by user kelemeng.: 2169 of 5452 strings translated (3 fuzzy).
Commit from Mozilla Verbatim by user toniher@softcatala.org.: 2080 of 5452 strings translated (7 fuzzy).