ClientStreamingSurfaceActiveCall.php

SurfaceActiveCall.php was split into four files. Each file must contain exactly one PHP class because of the following line in the spec:

> The terminating class name corresponds to a file name ending in .php. The file name MUST match the case of the terminating class name.

Other changes were made to correctly import the library using the autoloader.
	Change on 2015/01/02 by mlumish <mlumish@google.com>
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=83150065