refactor($location): move file://+win path fix to $location

The urlResolve method was fixed to automatically remove the
volume label from path names to fix issues with the file
protocol on windows where $location.path() was returning
paths where the first segment would be the volume name,
such as "/C:/mypath". See #4942 and #4928

However, the solution was specific to the $location non-
HTML5 mode, and was implemented at a lower level of
abstraction than it should have been. This refactor moves
the fix to inside of the LocationHashBangUrl $$parse method.

Closes #5041
feat($attrs): add $attrs.$attr to externs so that it isn't renamed

This fixes the issue that any usage of $attr is broken after js compilation.
Merge branch 'master' of https://github.com/angular/angular.js