Updated Brazilian Portuguese translation and proofread
Updated Polish translation
Uploaded Ukranian
Updated Spanish translation
Render: don't use the caps name for the muxer / encoder caps.

Instead use their stringified version.
Makes us able to render in MP4 and MPEG-TS.
bin: git-environment: Fix mixup in variable names
Updated Traditional Chinese translation(Hong Kong and Taiwan)
copitmizations: Fix mistake with pycairo header import

https://bugzilla.gnome.org/show_bug.cgi?id=715125
Allow disable help
Updated Czech translation
bin: Handle gi typelib path
[l10n]Updated Turkish translation
system: Use the system instance for displaying notifications
system: When the notification daemon is dead get over it
system: Fix debug statement
system: Remove System._listToString
system: A bit more Pythony
Get rid of assert False
dogtail tests: Use the filechooser's path togglebutton instead of the "/" key

This removes a trick where we simply typed the "/" character to force open
the path entry in GTK filechooser, checking for the state of the togglebutton
and clicking it if needed.

While theoretically slower, the actual performance impact is mostly negligible:
for example, the medialibrary test takes 20.8 seconds instead of 20.7.
dogtail tests: Add some sleeps to prevent false alarms on some tests