Add feed_url to feeds

Need to separately store url and feed_url
Refactor feed model and feed parser

Use class level methods for all methods in FeedParser
Refactor Feed model
Fix loading by api_key
Refactor feeds controller for API
Use Sanitize gem
Create new Scrubber class

Delegate methods to scrub article data, can also be used to scrub other
attributes. Set whitelist attributes within HTML module for use
elsewhere.
Merge branch 'master' into front-end
Bump Angular packages.
Split configuration into separate files.

This is more in line with the Rails way of doing things.
May as well carry the pattern over to scripts.
Keep it strict.
Fix scrubber

Remove lambdas, unnecessary.
Respond properly when feed is unavailable
Add conditional to CSRF check
Refactor feed parser
Check on https redirection

Rescue block was not being hit upon redirection so #discover_https_rss
will have to be hit separately.
Merge remote-tracking branch 'origin/master' into front-end
Restructured JavaScript files.

This cleans up the Angular app a bit.