Feature Proposal: friendlier dsl for finding elements

Hi, I'm finding it a bit painful typing protractor.By.xxx all of the time.  I threw together a quick spike (read no tests... yet) to gauge if there'd be interest in providing some shortcut methods in findElements.  This branch introduces first and all.

`ptor.first("selector")` is equivalent to `ptor.findElement(protractor.By.css("selector"))`. Similarly, `ptor.all("selector")` is equivalent to `ptor.findElements(protractor.By.css("selector"))`.  

I chose css as the default locator strategy because its the most generic. If you'd like to use another locator strategy you pass it first and the selector second.  For example `ptor.first("binding", "someBinding")`.

Thoughts?