feat(ngBindOnceDirs.js): implementation of simple bindOnce directives

I have not seen or heard anything from the core team regarding the bindOnce issue, but I bet you guys are working on something, regarding the amount of +1s #5408 has received. But since I have not seen anything I thought someone would like this.  

This is a super simple implementation which introduces many useful directives into the core with very little code. It has almost full parity with the popular bindonce library, in terms of the amount of directives it offers. It also works with promises, $timeouts, and any other values that are set after the initial digest. 

I did not want to create all the Docs for each directive just yet. Wanted to get some feedback on whether or not this type of functionality would be merged in or not?