Please note that this is a squshed commit and the work of:
Symbolist, macdiesel, nedbat, doctoryes, muzaffaryousaf and muhammad-ammar

Also, I replaced a number of tearDown methods with addCleanup instead.
And also remove some unneeded patch.stopall() calls.

Modify Django's translation library, such that the gettext family of
functions return an empty string when attempting to translate a
falsey value. This overrides the default behavior [0]:
> It is convention with GNU gettext to include meta-data as the
> translation for the empty string.

This patch provides a holistic solution to replace the current piecemeal
approach [1][2].

Affected Methods:
    - gettext
    - ugettext

[0] https://docs.python.org/2.7/library/gettext.html#the-gnutranslations-class
[1] bad803e4
[2] https://github.com/edx/edx-platform/pull/4653