Create external watchdog monitor driver class source and header files. see #15
Add method to enable EWM peripheral module. see #15
Add EWM driver methods to enable and disable the EWM input port and the EWM interrupt. see #15
Add methods for selecting the EWM assert state and servicing the EWM watchdog. see #15
Add methods to set the EWM clock prescaler and the low and high compare values. see #15
Merge master to cr-15.
Protect against writing to write-once EWM registers more than once. see #15
Update Freescale peripheral memory map header file include. see #15
Merge cr-15 to master.