correction to callback invokation.

This was allegedly expected to call `callback` with any arguments beyond `msg` and `callback`. The code being corrected was calling `Array.prototype.slice(...)` which attempts to slice `Array.prototype` and not `slice`'s first argument. I think the intention was to call `Array.prototype.slice` in the context of `arguments`, passing `2` as the 1st parameter.
Merge pull request #262 from MicronXD/patch-1

Correction to callback invokation.
Fix push --watch not noticing changes that occurred during a push (fixes #264)
Update google-play-services plugin
Create faq.md
[nit] Spelling Fix
[nit] Consistent usage of term 'CCA apps'
Update FAQ expanding on a few points
Fix minor typos in faq.md
Update faq.md

Spelling of "Stack Overflow"; also added note about reading docs if using plugins outside of cca
FAQ - we do enforce CSP of inline scripts
FAQ: Clarify Polymer support