Fix lazy() ClassCastException and DataBinding tests

Fix #363 : form.submit()

Some fixes needed to run gquery with gwt-2.8.0-SNAPSHOT

Data binding over list attributes

null accordingly.

When using gwt-2.8.0 and java8 gwt compiler is more restrictive and
when you override a method(Object) with certain classes like
Interfaces or JSO, there is an error like:
The method $(Object) is ambiguous for the type GQuery.

Also updated lazy interface with new methods.

Updated jquery and Sizzle librairies for the benchmark sample

Added SafeHtml as alternative to html string.

As ClientBundle do, it's now possible to use relative or absolute path
to load js libraries in JsniBundle.

Use absolute path to load library in JsniBundle

As ClientBundle do, it's now possible to use relative or absolute path
to load js libraries in JsniBundle.

Some fixes which should be in current version