Add Facebook integration

[techieshark]

Lots of people are on Facebook. The bot should be able to post to a Facebook page too (in addition to posting to Twitter).

[t-pfaff]

And Instagram!

[techieshark]

@t-pfaff good idea! That could actually be it's own separate issue I think.

[boonrs]

Last year at an open source hackathon instagram was explored but it turns out you can't post. Here's the pertinent info from that page:

At this time, uploading via the API is not possible. We made a conscious choice not to add this for the following reasons:

• Instagram is about your life on the go – we hope to encourage photos from within the app.
• We want to fight spam & low quality photos. Once we allow uploading from other sources, it's harder to control what comes into the Instagram ecosystem. All this being said, we're working on ways to ensure users have a consistent and high-quality experience on our platform.

[dillondrobena]

Facebook should be added in request #25