Prefer exact matches in the named selector

This uses the approach implemented by @bevanr in #386 but rebuilds it on
top of the latest Mink where the NamedSelector was changed a lot.
It also supports using the 'named' selector for findAll call, which was
not the case in the original implementation.
Renamed the exact and partial named selectors
Added a BC layer for the named selector in the handler

This BC layer will ensure that code using the SelectorsHandler directly
will not break when trying to access the named selector. However, it will
trigger a deprecation notice.
Marked HHVM as officially supported
Updated the doc for the branching changes
Added tests for evaluateJavascript
Merge pull request #465 from stof/js_tests

Added tests for evaluateJavascript
Added a few more cases for the evaluation of scripts
Marked the new test as skipped when the method is not implemented yet
Improved the handling of skipping tests for unsupported actions

Catching the UnsupportedDriverActionException everywhere to skip the tests
is totally ugly. Using the dedicated PHPUnit extension point is simpler,
and will support all tests easily.
Split the MouseOver event into several tests

Selenium1 and Selenium2 drivers are both marking this test as incomplete
and duplicating part of it for the events they support, so that these
events can be tested without being skipped because of other unsupported
events. Because of this, it does not make sense to have them in the same
test.
Added tests for all keyboards modifiers
Merge pull request #451 from stof/prefer-exact-matches

Prefer exact matches in the named selector
Added a hook to wait before doing the assertion for PhantomJS
Merge pull request #466 from stof/improve_testsuite

Improve the testsuite
Merge branch 'develop'