Adding option to give tabs custom Ids and to turn off URL hash and browser history manipulation

Hi,

I've been trying out your plugin in a couple of projects and it's awesome.

I've made a couple of additions to the browser history side of things - it can now be turned off in the options, and if it is left on, you can give tabs custom Ids for use in the URL hash by applying id attributes to the list item elements in the html.

Hopefully these additions might be useful for others too? Sorry about the three reverted commits! I was trying out the git plugin for Visual Studio and it was messing up the encoding of files and thus mangling the diffs, so I ended up reverting and re-applying my changes from scratch.

Ben