Fix tweet.coffee for v1.1 API

After the API retirement, this stopped working. This updates it to use
the ntwitter package, and follows the same configuration conventions as
tweet-mention.coffee for re-use.

It does depend on a fork of ntwitter though, and will need to be so
until AvianFlu/ntwitter#110 is fixed
Merge pull request #992 from github/fix-tweet-coffee

Fix tweet.coffee for v1.1 API