Upgraded Guava to unmodified v18.0

This simply copies the Guava source for v18.0 straight from the
github repository into this one.

See https://github.com/google/guava.git

Additional commits will be made which will allow this to compile
on Android.

BUG=19672715

Change-Id: Ief2c7a00b4456aa03ce3ca73db34cb86abdbad14
439 files changed