Add system integration module peripheral driver class source and header files. see #6
Rename system integration module driver file and class names. see #6
Merge master to cr-6.
Clean up SIM driver comments. Add SIM driver class data member containing array of system clock gating control registers. see #6
Add system clock gating enable and disable methods to SIM driver class. see #6
Replace direct configuration of PIT system clock bit in main function with call to SIM driver class method. see #6
Change type of system clock gating control register array elements. see #6
Merge cr-6 to master.