build for release 3.1.0 to NuGet

* post function will now use a Web API error response text for display
to user, with fallback to prior message logic.
* added datepicker plugin
* fix autocomplete and listbuilder async plugin for proper widget use
* on button click, the json data used has a final fallback value of the
button's data attributes instead of null.
* on view template toggle, it better handles the case of when 'cancel'
type actions were for an add that should not toggle or if for an edit
that should toggle back to a view.
* consistent casing checks on form method
* some formatting changes
nuspec publishing updates

project url change, title added, other notes moved.