[PATCH 0/6] Add test cases for GAtServer

[Zhenhua Zhang]

These patches register callback functions for each AT command.

Patch #1-#5 register basic commands into gatserver.c.
Patch #6 add a simple voice call test case in test-server.c.

TODO:
1. ATE,ATV,ATQ could share a template function.
2. Register more basic commands defined in 27.007.