Added closeButton option

The bootstrap-inspired link no longer needs to be part of the content.
Added toggle() method
Overwrote getContainer() and added setContent() method
Added listing-markers example
Added isVisible() method
Fixed click events in sidebar
Added example listing to main example
Added Compatibility section to README
Added two-sidebars example
Added .gitignore file
Added npm package.json file
Fixed jshint issues
Use grunt for building minified distribution
Fixed csslint issues
Added csslint task to Gruntfile
Added 'lint' and 'build' tasks to Gruntfile
Added 'package' task to Gruntfile