support setting url #fragments in state params

As per @sadlerw's request in #701

NB: obviously HTML5 mode needs to be enabled for this to have any effect
Supports both formats:

* `ui-sref="mystate(myparams)#{{ myhashexpression }}"`
* `ui-sref="mystate({myparam1: myvalue1, myparam2: myvalue2, '#': myhashexpression})"`