Implement client-side Firebase Cloud Functions locations (#23)
* Implement client-side Firebase Cloud Functions locations
Allows client-side Functions calls to remote functions using a supported
Region (Android & iOS) or Custom Domain (iOS only).
See
https://firebase.google.com/docs/functions/locations#client-side_location_selection_for_callable_functions
Adds a method to FirebaseApp ('functions') to set Region or
CustomDomain.
Example usage: firebase().app().functions("europe-west")
See
https://firebase.google.com/docs/reference/node/firebase.app.App#functions
Example client-side call:
firebase().functions().httpsCallable('functionName')()
calls Cloud Function:
exports functionName = functions.region('europe-west1')...
See
https://firebase.google.com/docs/functions/locations#best_practices_for_changing_region
Supported regions: See
https://firebase.google.com/docs/functions/locations
By default functions run in the "us-central1" region, unless another
region is selected.
Android Functions Emulator: Set 'localhost' host to 10.0.2.2
* Update README.md file with usage instructions
* Update README.md file with usage instructions
* Clenaup README.md text
