3-3-20: Added create new content from file endpoint for API and Android SDK

You can now submit file uploads via multipart uploads: https://developers.pixlee.com/reference#create-new-content-from-file

The Android SDK has been changed to reflect the above ability as well: https://github.com/pixlee/android-sdk/releases/tag/1.3.0

Stay tuned for an equivalent iOS SDK update in the coming week!