Allow callers to set value of notifyAuthFailure

Since a caller might want AndroidAuthenticator to show a notification
instead of delivering an error, allow it to be specified.

Change-Id: I9232668f4e8e83b46da2c2fb1c678246c735f200
Merge "Allow callers to set value of notifyAuthFailure"
Only disable URLConnection useCaches if Request shouldCache is enabled

Change-Id: I00e2162c0f8b191a48c3694fbe8360ceca41696a
Add Request defaultShouldCache property

defaultShouldCache is a static property to set whether or not a Request should cache by default

Change-Id: I4e1c0303b9ce8b93381217a1205cde19ce217982
Set project as library project

Change-Id: I10e946f5402f95e5cdee9a999d420df1971c6fc5