RATE_LIMIT default settings
Support for a redis instance as startup argument
ratelimit decorator for all http method functions
Rate-Limiting implementation logic
'X-RateLimit-' response headers
Don't attempt Rate-Limiting if app.redis is not set
Default Rate-Limit set to 300 requests/15 minutes
'utils.request_method' helper function

'utils.request_method' returns flask's request.method, but taking our
support for PATCH alternative (POST with the 'X-HTTP-Method-Override'
header) into consideration. This helper function allowed for some nice
refactoring in the code.
Rebase conflict solved
Rate-Limit: Not failing on HEAD requests anymore
Tests for the Rate-Limiting feature
Rate-Limit enabled for API homepage
Rate Limiting documentation
Rate Limit on changelog
Test for disabled Rate Limit
Merge branch 'rate-limiting' into develop. Closes #58.
redis added to 'test_requires'