Use mavenCentral instead of bintray

[hstorz]

Since the bintray url is down and only returns 502 a switch to mavenCentral is required.

[nithinyell]

This is true

FAILURE: Build failed with an exception.

* What went wrong:
Could not determine the dependencies of task ':app:lintVitalRelease'.
> Could not resolve all artifacts for configuration ':app:debugRuntimeClasspath'.
   > Could not resolve com.facebook.fresco:animated-gif:1.+.
     Required by:
         project :app
      > Failed to list versions for com.facebook.fresco:animated-gif.
         > Unable to load Maven meta-data from https://dl.bintray.com/microsoftazuremobile/SDK/com/facebook/fresco/animated-gif/maven-metadata.xml.
            > Could not get resource 'https://dl.bintray.com/microsoftazuremobile/SDK/com/facebook/fresco/animated-gif/maven-metadata.xml'.
               > Could not GET 'https://dl.bintray.com/microsoftazuremobile/SDK/com/facebook/fresco/animated-gif/maven-metadata.xml'. Received status code 502 from server: Bad Gateway

[tw0po1nt]

Thanks for this. This should definitely get merged, but I wonder if it ever will, since it looks like the last PR to merged was about a year ago. This repo is getting stale.