heart : upgrade HEART-battery

heart : upgrade HEART-battery

1) Stability
  - Use enum for charger status instead of integer
  - Fix memory leak
  - Asynchronous (level)DB updating

2) New function
  - Discharge rate : HIGH(1.2x~), LOW(~0.8x), compare with predicted rate
  - New logic for battery remaining time estimation
    - Calculate SOE(State Of Energy) decreasing rate
    - SOE is considered to the integral of OCP(Open-Circuit Potential)
    - To use new logic, vendor have to support battery capacity and OCV coefficients

Change-Id: Ic80073028d8fde16980a53d8cb550023b56cb8b8
Signed-off-by: Kichan Kwon <k_c.kwon@samsung.com>