commander: Isolate plugin loading.

Refs #7.
plugins: Look for loader.

This kind of "iterate over the plugins" could probably be factored.

Refs #7.
commander, plugins/quote: Isolate database configuration.

Not sure if this works for quotes, since that plugin appears to not register
commands correctly. What is up with that?

Refs #7.
commander: Remove plugin add/remove from the IRC client.

And update the plugin plugins to match.

...At some point, "plugin" starts to look like a very funny word.

Refs #7.
commander: Isolate plugin running.

At this point, we've pulled everything out. All that remains is to unknot some
of the execution.

Refs #7.
commander, plugins/bitly: Pass in configuration on plugin loader.

Remember, kids, don't code while tired.

Refs #7.
commander: Remove CommanderFactory.registerPlugin().

And fix its only use.

Refs #7.
Merge pull request #9 from MostAwesomeDude/plugin-loader

Separate plugin loader from commander.

Thanks Corbin!