1. Fix sentence breaks inside `photo_reverification.html` and `midcourse_photo_reverification.html`.
2. Combine three setences inside `choose.html`.
3. Adding some punctuation marks to reduce duplicated strings with only different Punctuation marks in translation.
4. Move the colons inside the strings to be translated. This may be not necessary for now, but I think this may help translation by removing potential word meaning conflict.
5. Sorry for

1. Fix the broken `gettext()` call in `courde_detail.js`
2. Change the string to avoid Transifex misunderstand the pattern '% o' in `checklist.underscore`.
3. Embed the `{filename}` part inside the string in `transcripts-choose.underscore` to provide better i18n flexibililty.
4. Remove all the call of `gettext()` and `${_()}` inside the `mock` directory to aovid mis-extraction by pybabel. (It seems that the `mock` directory is soly used in test? So the strings in this directory need not to be extracted and translated?)
5. The unicode char `\u2014` will trigger a bug inside pybabel which makes the extracted string untranslatable, so remove this char.

1. Spliting strings inside the call to `gettext()` in javascript breaks the string extraction process, so the string should kept in one line.
2. Using escape string inside a string in `gettext()` may cause the extractor to misunderstand the escape string, so that it will escape this escape string.

* updating vendor files
* updating class syntax (to new FA-based classes) for all UI elements
* correcting broken tests

TNL-997

Fix donwload subs for non youtube videos and non-en language - continue.
Add acceptance tests.
Add detetion of assets on request.
Updated docstring.
Add fixes and acceptance tests.
Fix acceptance tests.
Update docsrtings and cleanup code, resful for language_id.
Specify exception type in POST.
Fix url in upload module.
Improve exception handling.
Remove 'en' and catching in editable_metadata.
Move descriptor.get_context test to lms tests.
Add query parameter to translation dispatch.
Response to format parameter of translatin GET request.
Fix Acceprance test: Metadata Editor.
move handlers to proper scores.
Split video player into smaller files.
Add ugettext and fix typoes.
Add changelog.
Support for downloading non-ascii filenames.
Change event binding.
Add content-language to download requests.
Reractor POST handler to not update self.transcripts.