SDK is very Large (~8MB) and has a high method count

This library needs to be shrink down. Currently it has 19829 method count which is way to large.

Below is the break down of the method count taken from http://www.methodscount.com/?lib=com.dropbox.core%3Adropbox-core-sdk%3A2.0.1

Library name: com.dropbox.core:dropbox-core-sdk:2.0.1
Total count: 19829

Methods count: 9087
Dependencies: 3
JAR Size (KB): 1897
DEX size (KB): 1214
Dependencies methods count: 10742
Dependencies JAR size (KB): 1503
Dependencies DEX size (KB): 1346