Added Optional Binding Options

* optional binding options can be specified as function parameters, 'data-binding-options' attribute or in a data-template-bind attribute
* added tests for basic use cases
* added examples for optional bindings
* updated readme.md with new features


Note:
I have not yet had time to test the new feature with nested templates.
Also, if you create a new release, update the version of jquery.loadTemplate-X.X.X.js in Examples/index.html.