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
Added .clang-format file

Added .clang-format to specify the code format for the project.
It relies on the tool clang-format. clang-format is not shipped
in xcode command line tools. To use clang-format inside xcode
download and install clangformat-xcode
https://github.com/travisjeffery/ClangFormat-Xcode

Updated contirbuting to add insturctions on setting up
xcode to use clang-format
Merge pull request #81 from cloudant/clang_format

Added .clang-format file
Allow setting certain HTTP headers for replication

Allows one to set optional HTTP headers for replication during the configuration
of an individual CDTPull/PushReplication object. This does not set these
headers globally.  The optional header property is found in the
CDTAbstractReplication class (which 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
used to gain access to all NSURLRequests made during replication.
This class passes the NSURLRequest to a delegate that tests the headers.