configure.ac: post release version bump to 3.12.2
Python 3.4 make check fixes

Use unittest.skip() instead of unittest.expectedFailure() for tests which
pass in GI 1.39.0. This is needed to get rid of unexpected successes which
fail unittesting in Python 3.4.
Silence deprecation warning when using imp.reload.

https://bugzilla.gnome.org/show_bug.cgi?id=730411
PEP8 fixes

Use infix 'not' instead of prefixed.
Don't use double comments (##).
Use space between comment and text.
Un-comment tests that now work.
Move broken (and won't fix) implicit int64 signal tests into
a new skipped test function.