Add new file with common functions for tests to use.
- loads config file
- checks for mcexec etc
- checks for LTP and OSTEST if required
- handle mcstop / mcreboot if required, and provide function for it
At the same time, make a few changes to mck_test_config:
- move to ~/.mck_test_config
- add boot params to the config, tests the require specific params can
overwite it
- make the config "set-if-variable-is-empty", so someone can overwrite
any param by setting the environment value e.g. LTP=.... ./test.sh
will use the value given
Change-Id: Ib04112043e3eb89615dc7afaa8842a98571fab93
