chore($resource): Use shallow copy instead of angular.copy

Replace calls to angular.copy with calls to a new function, shallowClearAndCopy.
Add calls to copy for cache access in $http in order to prevent modification of cached data.
Results in a measurable improvement to the startup time of complex apps within Google.

Closes #5300
chore(Angular.js): Use call and === instead of apply and == in type check functions

Updates isDate et al to use call instead of apply and === instead of ==.
The change to call brings minor performance improvement and === is just
better practice than ==.
http://jsperf.com/call-vs-apply-tostring

Closes #5295
Merge branch 'master' of https://github.com/angular/angular.js