erlang module thriftTest_thrift referenced instead of thrift_test_thrift

Both the lib/erl/README.md as well as lib/erl/test/test_server.erl mention a reference to thriftTest_thrift.

Running test_server:go() will not fail until a client attempts to connect.

make creates the right modules and hrl files for thrift_test_thrift,
and using this instead allows the client-server example in the README.md, to work as advertised.