Replace prototype with jquery - references to focus function

Replaced prototype references to the focus function with the equivalent in jquery following the pattern below:
prototype: $('id').focus()
jquery:    $j('#id').focus()

https://github.com/ManageIQ/manageiq/issues/214
@dclarizio, not a typo, just checking for the element existing prior to focusing.  That is the preferred way to do so per http://learn.jquery.com/using-jquery-core/faq/how-do-i-test-whether-an-element-exists/.  Could make it more readable by creating and calling a custom function, but doing so is much more expensive than a simple property reference.