updated the code to 2.0.0 release

This updates the code from the 2.0.0 beta to the 2.0.0 final version.
make sure we flush and use insert not upsert
update all screenshots

this also fixes #11
expose the sync and async bucket
added test for sync bucket + ajust presentation
Merge pull request #14 from couchbaselabs/update-java-samples-to-2.0-sdk

updated the code to 2.0.0 release