CDTPullReplication constructor parameter types are wrong

[pwcremin]

e.g. In CDTPullReplication the 'target' is type CDTDatastore, it should be NSURL.

@implementation CDTPullReplication

• (instancetype)replicationWithSource:(NSURL )source target:(CDTDatastore )target

@implementation CDTPushReplication

• (instancetype)replicationWithSource:(CDTDatastore )source target:(NSURL )target

[tomblench]

For pull replication the source is a remote database (NSURL) and the target is the local database (CDTDatastore).

For push replication the source is the local database (CDTDatastore) and the target is a remote database (NSURL).

See our documentation for more details, including the code samples in https://github.com/cloudant/CDTDatastore/blob/master/doc/replication.md