Remove the github plugin dependency to start bot

[goduncan]

• This change moves the github plugin to the command_plugin directory allowing the bot to be run with only a Slack Token.
• Idea is to use hubcommander as generic python Slack bot framework for people to build on.

[mikegrima]

I'll try to take a look at this later this week.

[mikegrima]

I'll need to see how this works with regards to plugins that make use of GitHub.

For example, I'll need to see how the Travis CI plugin would work with this change.

[mikegrima]

@goduncan : Been busy lately -- didn't forget about this. Can you resolve the conflicts?

[goduncan]

No worries. I haven't had time to test if the Travis plugin works as before with the changed but the bot starts with it enabled.

[goduncan]

Hello. Do you still think it's likely that you will be merge this?

[mikegrima]

Hi @goduncan ! I will look at it today. I PROMISE!

[mikegrima]

You will need to make a change here: https://github.com/goduncan/hubcommander/blob/develop/command_plugins/travis_ci/plugin.py#L72

GitHub is a dependency for Travis CI.

I'll come up with the sample fix.

[mikegrima]

@goduncan The PR looks good.

I will submit a follow-up PR with the additional fixes for Travis CI.