Always add Plural metadata to dummy translations.

When this was conditional, we'd have plural info in some files, not in
others. Then we'd merge them, and msgcat would add wacky markers to
indicate the difference, and the metadata wouldn't parse.
Tighten up the extraction I/O

We were writing the main file twice.  No need.
Give numerical response tolerance as a range (for example [5,7)) (BLD-25)
Merge pull request #2231 from edx/alex/numtolerance_range

Alex/numtolerance range
BLD-711: Fix offest in FF.
Merge pull request #2303 from edx/ned/i18n-tool-fixes

Ned/i18n tool fixes
Merge pull request #2315 from edx/anton/fix-imageresponse-offset-in-ff

Imageresponse: fix offset in FF.
annotation tools
First set of fixes from the pull request

This does not include some of the testing files. The textannotation and
videoannotation test files are not ready. waiting for an answer on the
issue.
Deleted token line in api.py and added test for token generator
Added notes_spec.coffee
remove spec file
fixed minor error with the test
fixes some quality errors
fixed unit test
fixed unit test
added advanced module
Added notes_spec.coffee
remove spec file
Quality and  Testing Coverage

1. in test_textannotation.py I already check for line 75 as it states
in the diff in line 43, same with test_videoanntotation
2. Like you said, exceptions cannot be checked for
firebase_token_generator.py. The version of python that is active on
the edx server is 2.7 or higher, but the code is there for correctness.
Error checking works the same way.
3. I added a test for student/views/.py within tests and deleted the
unused secret assignment.
4. test_token_generator.py is now its own file