Dev: Added hashGenerator option

I have added a `hashGenerator` option.

  * Fully test driven
  * `hashGenerator` can be `"compact"`, `"pretty"`, or a `function(text,element){ }` that returns the hash value.
  * Updated Change Log
  * Updated minor version number
  * Added option default and doc comments

NOTES

  * Could not install grunt easily so there is no minified version (and therefore it's untested)