Migrate to simulator.

[karajan1001]

Using simulator can:

1. greatly accelerate the tests ( can be executed parallelly).
2. Provide other users a way to run the tests.

[karajan1001]

Pending for :

1. too many unsupported methods in the emulator
2. some differences between the emulator and the real server.

Would be continued if the emulator begin to update or new emulator appears.