feat(locators): Added a By.cssContainingText locator.

This new locator find elements by css selector and inner text in response to the lack of ':contains' selector.

Example: By.cssContainingText('ul .pet', 'Dog') will find all ul children with class 'pet' containing the text 'Dog'.

Closes #488, Closes #709
fix(locators): using $().$$() should return an ElementArrayFinder

Prior, $(foo).$$(bar) would return a promise which resolved to an array of
WebElements. This is unexpected, since $(foo).$(bar) returns an ElementFinder, and
element(by.css(foo)).element.all(by.css(bar)) returns an ElementArrayFinder.
Fixed so things are more consistent.

Closes #640
fix(cli): fix --exclude command line flag

Accidentally got changed to 'excludes'. As discussed earlier, should be single
to be consistent with Karma.

Closes #637
test(synchronization): show that synchronization works with ng-included content
fix(mocha): fix it.only so that it does not double-wrap

Closes #649