Call validateRevision from forceInsert.

Added the logic to call validateRevision in the forceInsert to check that the
current revision abides by the validation (if any). The logic is copied as
it exists in the iOS version.

Issue Reference: https://github.com/couchbase/couchbase-lite-java-core/issues/206
Set the historycounter to start from 1

Since the revisionHistory is passed in descending order, we want the last
successful revision to be set as the "oldRev" property in ValidationContext.
Fix this by starting the counter index from 1 instead of 0
Minor code reformat
Issue #206 - remove unneeded call rev.copyWithDocID

Also add some TODO's in the code to get it more in line w/ iOS version.

https://github.com/couchbase/couchbase-lite-java-core/issues/206