Adds support for filtered push replication.

This commit adds support for filtered push replication via the CDTPushReplication
interface. A developer supplies the definition of the filter via a CDTFilterBlock,
and the query parameters via a NSDictionary.

* Adds CDTPushReplication -filter and -filterParams.
* Modifies CDTReplicationFactory -oneWay:error: to wrap the CDTFilterBlock
inside a TD_FilterBlock and into the source TD_Database so that TDPusher finds
the filter during replication.
* Adds tests in Tests project DatastoreCrud.m and CDTReplicationTests.m.
* Adds tests in ReplicationAcceptance project.
* Improves some documentation in CDTPullReplication and matches that in CDTPushReplication.
Check the style used by Apple for their docs, e.g., for [NSDictionary](https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/Reference/Reference.html).

It's a little more concise, but mostly it's more impersonal. For example, "Use CDTReplicatorFactory to create CDTReplicator objects based on the parameters set in a CDTPushReplication or CDTPullReplication object.". The sentence starting "Note that you" is a good example of the style, though I'd be more specific, and note that CDTReplciatorFactory must be started before CDTReplicator.