UI Updates

# Work in Progress

![mruby-web-irb](https://f.cloud.github.com/assets/4437/442015/e700c0a8-b132-11e2-998e-ae2a46803ddb.png)

Being that IRB is the workhorse of any ruby toolchain, thought it would be nice to put some work into the UI. 

The approach follows that of the chrome/safari web inspector tool, which splits command mode and edit mode into a 2 column view.

In the command view, type any ruby code and hit `Enter` to see result. Use `Up` / `Down` arrows to navigate history. History is stored in browser locale storage :D

In the editor view the user can click `Shift` + `Enter` to run entire listing.

The jist of it is there, so please give it a try and let me know what you think. If this is a direction you would like to move in.

Here are some todos I am still working

- [ ] add resizable splitter
- [ ] ability to hide/show code editor window (like chrome web inspector)
- [ ] remember splitter dimensions preferences in local storage
- [ ] remove "Clear editor after submitting options" use reset command instead (gives more control). in addition they can hit F5 and refresh the page since we store command history in localStorage   
- [x] user can hit shift-enter to submit code listing
- [ ] show welcome overlay popup on first visit with overview and "try it now/start now" button
- [ ] remember that the user saw welcome popup in local storage
- [ ] add "help" command, should popup with list of keystrokes and examples
- [x] add fork me on github logo
- [x] use monospace font
- [x] clicking anywhere in shell should focus input
- [ ] handle recalling multiline commands
- [x] store history in browser local storage
- [ ] store edits made in ace code editor in local storage
- [x] add basic stylesheet with sass, update readme with instructions