fix #1178 multiple issues when dragging within a parent container that is scrollable

close #1179

Also partly fixes #695 one of the failing test for IE7/8: test.aria.utils.dragdrop.OutOfBoundaryTest now passes
fix #1123 rename History `onpopstate` event to `popstate`

This change has been done to be more compliant with the standard HTML5 spec.
Both events are still present, and both of them are fired when needed.

DEPRECATES: the `onpopstate` event in History class.

Use `popstate` event instead.

Close #1224.
refactor cleanup dead code after #1057

Commit d46d7dd5a938591d6fd8b05622ec4b709e50f389 removed certain
functionalities regarding the usage of `postHeader` but some related
code was not removed properly.

This commit cleans this up by removing the framework code that was
effectively dead as of 1.6.1 (passing a param that was not taken into
account).

The removed test was passing because the cfgbean had `$restricted : false`
hence JSON validator was accepting even the keys removed from the cfgbean
in the earlier commit.

Close #1227.
feat #### Add grunt tasks to ease packaging

This commit introduces
- a grunt multi-task (`atbuild`) that allows to simply re-package aria templates source code. It is also used internally for the production build of the framework.
- a grunt multi-task (`easypackage`) that allows to create packages for an aria templates-based application. It simplifies the configuration that is generally needed in order to achieve this goal by exposing a simple API to the developer.

These tasks are now available in any project including the framework. The necessary files are published to npm along with the framework and there is no need to explicitly add atpackager or noder-js as dependencies in order to execute them.

Close ####