Restore unintentionally deleted tests

Restores tests that were accidentaly deleted
during the purge of old API specfic tests

Also removes test that deletes a document
revision from conflict resolution as this
is currently not supported
Merge pull request #68 from cloudant/restore_deleted_tests

Restore unintentionally deleted tests
Creates individual threads for each TDReplicator.

This commit moves all of the threading code from TDReplicatorManager
to TDReplicator so that each TDReplicator executes on its own thread.

No new tests are yet written to monitor multiple replications at
once.
Fixes security issue where passwords were being sent to the log.
Adds test for multithreaded replication.

Two pull replications are executed simultaneously, pulling
from the same remote database to two different local databases.
A delegate captures updates from the replicators and determines
if the replicators were operating simultaneously.