HTTP api

[mtbentley]

This would allow users of the api to add features w/out editing Go code, and instead communicate with the bot over an http api.

[mtbentley]

Example slacksoc api (after 5 minutes of thought):

1. @slacksoc: pm me a key, slacksoc pms an api key and token, saves those to the db w/ the username of the person who requested it
2. There's an endpoint to post a message (which supports many of the same options that the slack api supports)
3. There's also an endpoint to add callbacks, which registers a regex and a callback location, and slacksoc makes an http request to that location whenever a message matching that regex is sent (from there either the callback responds with an action, or can do something through 2)

[brenns10]

Somewhat similar in spirit to brenns10/slacksoc#16