feat #1292 Adding the ATValidateTemplates visitor in AT build and easypackage task

This commit adds the ATValidateTemplates visitor in the build and
as a configurable option in the easypackage task, so that templates
can be strictly validated during the build. This is especially useful
to find extra commas in JSON configuration objects inside templates.

This commit also adds some missing semicolons in the javascript code
generated from templates, as this is required for the ATValidateTemplates
visitor to accept templates.

close #1292
feat #1336 fullWidth property for TextField widget

Adding a new property to the textfield widget. This property allows to display the textfield as 100% width of its container.
doc #1337 add test showing handling of IO timeouts and 404s

This is mostly for documentation purposes for future reference
(no code change inside the framework).

Close #1337
Switching to attester 2.0.1.
Adding "npm run attest" script to easily run individual tests.

Here is an example:

npm run attest -- test.aria.AriaTest --browser=firefox

Any test specified in the command line will be run.
If no browser is specified, phantomjs is used.
fix #1340 compatibility with bing map

The Bing map javascript intercepts the events on body and prevents their propagation, so it is very important to be sure that the AT delegation system catches all the events at body level (i.e. not window)
close #1340
fix Error tooltip not displayed in a datepicker