ENH: Modularize cmake code for GT.M and Cache specific setup

Separated GT.M and Cache specific setups to different cmake
configuration files.

OSEHRA-Id: http://issues.osehra.org/browse/OAT-76
Change-Id: Ie7a111f39d06b4bdb634fd67f7ad2e53ac7d1148
Removed gtmroutines parsing dependency on MUnit testing

The 'gtmroutines' environment variable is parsed to extract GT.M source
directories irrespective of whether TEST_VISTA_MUNIT is checked or not.

OSEHRA-Id: http://issues.osehra.org/browse/OAT-76
Change-Id: Id48541dd8e18a16f109898b88621ab5e0aeed1f2