Added support for also indexing optgroup labels for each option

Fixes #26
Added bower.json

Also includes rake taks to auto-generate the bower.json

Closes #27
Respect disabled options when filtering and selecting values.

There is a new setting called showDisabledOptions that determines
whether an option shows in the list as disabled, or doesn't show up
at all.
Added examples for disabled options
Prevented all options from being disabled
Bumped to v0.6.0