Add support for multiline tweets.
Merge pull request #8 from pkwarren/multiline_tweets

Add support for multiline tweets.
Reply to the sender with the error if one occurred
botname "gesture"
Only return image results that have a 200 response header
Detect images using HTTP content type.

Changes the algorithm for looking up images from 'gis' plug-in to
perform a HTTP head request and then compare the resolved URL's
content type.
Update to return redirected URL.
Merge pull request #10 from pkwarren/better_image_detection

Detect images using HTTP content type.