Making some methods public

[Austinate]

Hi! First of all — thanks for such awesome tool!

I'd like to ask for few things (or just for a reply if that's not possible). Could we make this methods from GeoFire class public:

1. -(CLLocation *)locationFromValue:(id)
2. Location encoding code from - (void)setLocationValue:(CLLocation *)location forKey:(NSString *)key withBlock:(GFCompletionBlock)block Probably would be good to have something like -(NSDictionary *)jsonForLocation(CLLocation *)location)

And few words why do i need this: In my case i need to import large amount of entries into firebase (~100k right now). Right now to save location in GeoFire-compatible way i need to make 1 additional request via GeoFire per saved object or replicate code from methods i listed above. I think it'll be better to make such changes, so i'd be able to prepare location value in json without making separate request.

Please let me know what do you think about this. If it's ok — i'd be glad to make a PR with such changes.

Best, Ostap.