Update st abc walkingphase misc

Stabilizer, AutoBalancerを修正しました。
よろしくお願いいたします。

- Use contactStates in Stabilizer to specify single support phase or double support phase
- Fix USE_IMU_STATEFEEDBACK to USE_EEFM_STABILIZER for switching stabilizer algorithm and fix default debugLevel
- Fix transition between MODE_AIR, MODE_IDLE, and MODE_ST. Set MODE_AIR if startStabilizer is called in not on_ground condition
- Connect accRef from abc instead of seq. Note that connection from seq at previous revision is invalid and we should use sh instead of seq.  
If we can solve https://github.com/fkanehiro/hrpsys-base/issues/272 and https://github.com/fkanehiro/hrpsys-base/issues/285, I'll fix ``accRef`` port connection again to use both ``AutoBalancer`` and ``StateHolder``.