Changes:

• Added verifyCallback method for cryptographically verifying Coinbase merchant callback authenticity
• Tightened the cert pinning to root certs we actually depend on

Changes:

• Add new field to User

Changes:

• Add createUserWithOAuth method

Changes:

• Add method for revoking token

Changes:

• Add new fields to various responses
• Add method for generating OAuth authorization uri

Changes:

• Added type field to Account

Changes:

• Don't set price null on creating Buttons
• Compile for Java 1.6
• Support specifying custom base URL and SSL context
• Add OAuth methods

Changes:

• Change bks keystore format to support older versions of Android

Changes:

• Added idem field to Transaction
• Don't set transaction amount to null upon sending/receiving money

Changes:

• Add recipient address to Transaction
• Added more categories to AccountChanges.Cache
• Added merchant info to User
• Added specific UnauthorizedException for 401 errors