Add API exceptions
Basic FxA OAuth views
Validate token during authentication
Store dev DB in current folder
Better usage of API_VERSION
Default 999 for error number
Get rid of catchalls
Remove state and next when consumed
Exceptions subclasses named Errors
Simplify FxA views
Fix tests and PEP8
Refactoring
Document and test FxA
Rework README
Merge branch 'poc_fxa'