Update Commands

I'm removing Jekyll passthrough commands. Initially I thought it would be cool to mirror all Jekyll commands on Octopress (like hub does for git) but I've since decided that I'd rather only mirror Jekyll commands where running it under Octopress augments the Jekyll's version of that feature somehow.

- [x] Remove Jekyll passthrough commands
- [x] Add Isolate command
- [x] Add Integrate command
- [x] Add docs for new commands

Should you add `isolate` and `integrate` here?