check loginCallbackId exists before pluginResult call

We make sure that loginCallbackId exists before calling it. When it's not set, it triggers the exception referenced in issue #507
Update FacebookConnectPlugin.m

Tweaked the PRed code to be more inline with Google Objective-C style guide.
Merge pull request #1 from aogilvie/patch-2

Update FacebookConnectPlugin.m
Merge pull request #510 from jakecraige/patch-1

check loginCallbackId exists before pluginResult call
fix user.id to pass app validation - http://stackoverflow.com/a/14448057/3130279
Merge pull request #536 from machard/develop

fix user.id to pass app validation - http://stackoverflow.com/a/14448057...
version bump and spelling fix
Merge pull request #542 from aogilvie/develop

version bump and spelling fix
Merge pull request #543 from phonegap/develop

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