Internal connections only

[jcesarmobile]

This will append the random string to the User Agent and will only allow connections based on the User Agent containing that random string.

Bumped version to 2.2.0 as it's a big enough change, and also other already merged changes like the kit-kat support

[imhoffd]

@jcesarmobile You don't need to bump the version. It's done automatically during publish (along with git tagging, github release creation, etc).

[imhoffd]

@jcesarmobile Not finding WKBind, WKSuspendInBackground, or WKInternalConnectionsOnly in the Android code. Are they supported in Android? If not, we should make note of that.

[mlynch]

Looks good to me once we get some testing feedback from Brian and Matt re: deploy

[jcesarmobile]

@dwieeb yeah, those are iOS only, we can probably add WKBind, but the other two are not needed. Will edit the docs for now to specify that they are iOS only.

I bumped the version because Max bumped it to 2.1.5 in his branch and referred to that version in the readme, so I updated the readme to 2.2.0 and then bumped the version to avoid inconsistencies, but I can remove the bump if that will cause problems with the release script.