Revert "Include modulemap file to support module-enabled projects"

This reverts commit 2564c7c9f0c4bb1c1b3f30fc3a91daa3333ba5eb.
Podspec cannot refer to separate files

It looks like podspec files are pulled and processed by the pod tool
without the Version.h file in place. This cause the `File.read` command
to fail.
Adds ability to set optional HTTP headers in requests made during replication.

Allows one to set optional HTTP headers for replication during the configuration
of the CDTPull/PushReplication objects. The optional header property is found
in the CDTAbstractReplication class. It now conforms to NSCopying protocol.

Fixes a bug in TD_DatabaseManager.m that prevented headers to be set via
the 'properties' NSDictionary object used to create TDReplicator objects.

Adds tests for HTTP headers during replication

ReplicatorURLProtocol inherits from NSURLProtocol and is
a registered URL request in order to gain access to all
NSURLRequests made during replication.
This class does not manipulate or handle the HTTP requests, but
it does pass the NSURLRequest to a delegate to object that
tests the headers.