Update README.md

Added section on installation prerequisites. I had to figure out how to install them myself so thought I would add that info here. Also corrected the actual installation instructions.
Merge pull request #22 from jonlb/master

Update README.md
0.0.9
Fix for precision in Number.humanize.
Adding fireEventForElement support to date picker Behaviors. This allows the date picker to properly trigger Delegators.
Refactor Behavior.InputMirror to allow finer grained control of targets. Added support for keyup event.
update grunt file to put everything in dist/dev and dist/prod. Prod folder are minimized versions.
0.0.10
Behavior.HtmlTable's custom dataSortNumeric now supports floats.
Docs/config update.
Adding some licensing details.
Changing markdown docs references per changes to the behavior ui sandbox.
Added Ajax url history

* Adding `api.getBehavior()` to get the Behavior instance. 
* Adding support for pushing history changes via `api.fireEvent(‘updateHistory’, url)`.
* Adding this to Delegator.Ajax
Updated path to flat-ui
Adding behaviorInit event.
Minor HTML fix.
0.0.11
Updating to MooTools 1.5.1
0.0.12
Updating Behavior. Fixing link to jsFiddle.