Merge pull request #346 from murgatroid99/php_weak_comparison

src/php/lib/Grpc/AbstractSurfaceActiveCall.php

src/php/lib/Grpc/ActiveCall.php

src/php/lib/Grpc/ServerStreamingSurfaceActiveCall.php

src/php/tests/generated_code/GeneratedCodeTest.php

src/php/tests/interop/interop_client.php

src/php/tests/unit_tests/EndToEndTest.php

src/php/tests/unit_tests/SecureEndToEndTest.php

src/php/tests/unit_tests/TimevalTest.php