Upgrade gradle, build tools, and android gradle plugin to latest

Signed-off-by: Jacob Morris <jmorris@pivotal.io>
Upgrade junit

Signed-off-by: Jacob Morris <jmorris@pivotal.io>
Update travis configuration for latest build tools

Signed-off-by: Jacob Morris <jmorris@pivotal.io>
Merge pull request #48 from coreydowning/upgrades-dec-2014

Upgrade gradle plugins and junit