900mAH, er.... might not be sufficient to drive all 14 servo for long time. Yet, it depends on many factors. Do you need all 14 RC servo to be ON all the time? If so, easily it will take more than 14A, I afraid the battery will not "tahan" for 1 minute
Another thing you have to take care is the voltage. I think most of servo can only stand up to 6V, or 7.2V for higher power motor, but 7.4V li-po after fully charge is around 8.4V, it will definitely kill the servo before the battery cannot "tahan".
Hey, I think Cytron did a half body walking robot before, I remember they use some circuit to regulate the power to lower voltage yet provide high current. Check their site out. But 14 Servo is quite a lot of current, you might need to improve it. Good luck!