Update tzinfo to version 0.3.39
Update sqlite3 to version 1.3.9
Update multi_json to version 1.10.1
Update faraday to version 0.9.0
Update activerecord to version 3.2.18
Update json to version 1.8.1
Update pg to version 0.17.1
Update twitter to version 5.9.0
Use Active Support's String#truncate method to limit tweet to 140 chars

The length of an HTTP t.co short URL is currently 22 characters, as
specified here: https://blog.twitter.com/2012/upcoming-tco-changes

See also:
  * https://dev.twitter.com/docs/tco-url-wrapper/how-twitter-wrap-urls
  * https://dev.twitter.com/docs/counting-characters