Put some useful information in User-Agent Header

Put information in User-Agent:
* Build fingerprint
* Calendar or CalendarSyncAdapter package name + version code
* Package name of app making changes to provider for uphill syncs

Example:
google/mantaray/manta:K/MASTER/eng.aalbert.20121217.140040:eng/dev-keys:com.google.android.calendar:201212060:com.google.android.calendar Google-HTTP-Java-Client/1.11.0-beta (gzip)

Change-Id: Ief8f57809ce240df4f5c662c703dcb80dab47367