Updated PHP files to new method names

src/php/lib/Grpc/AbstractCall.php

src/php/lib/Grpc/BidiStreamingCall.php

src/php/lib/Grpc/ClientStreamingCall.php

src/php/lib/Grpc/ServerStreamingCall.php

src/php/lib/Grpc/UnaryCall.php

src/php/tests/unit_tests/CallTest.php

src/php/tests/unit_tests/EndToEndTest.php

src/php/tests/unit_tests/SecureEndToEndTest.php

src/php/tests/unit_tests/TimevalTest.php