Enable usage of custom headerSelector other than ‘h2’

- In this case, used of div.tabTitle
Hack in image replacement for IE8 tab hover woes
Add IE8 image replacement with error handling
Add public functions to activate/deactivate tabs
Add disabled state for deactivated tabs
Add deactivate support when using IE8 image replacement
Update minified version
Make activate/deactivate methods 1 indexed like other functions
Add ability to go to specific slide
Update readme
Change style for default tab header selector from div.tabTitle back to h2
More readme comments