Proguard messes with network-related code

[vickychijwani]

Somehow, inexplicably, Proguard has stopped working correctly sometime between commits 592abc3 (v1.0.1) and 2d3ea80 (see diff here). Login and revoke access token API calls are failing.

Proguard is preferred because it reduces the method count in Quill APK by nearly 50%. However if it looks like this will be a recurring issue, then maybe it's just not worth the effort.