First version of bigquery backend.
Lot of TODOs. But it should be good enough for anyone who wants to try
it out. Marked experimental.

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Merge remote-tracking branch 'upstream/master' into bigquery

	storagedriver.go

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Fix typo.

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Format fixes and small refactoring.

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Merge remote-tracking branch 'upstream/master' into bigquery

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Merge pull request #190 from rjnagal/bigquery

Initial version of bigquery backend.