add dualboot support for CWM

Change-Id: Ie80461fcaf462efc9d270b026e64053dcc3a8150
recovery: add truedualboot support

Change-Id: I80501250ee23146f57009d7968eb65b73e1fceaf
recovery: add support for switching bootmode

Change-Id: I8bc5770baae7a1342bedb8eddeb651a31f12f1b5