added -nodestroy option
Tests marked as setup or critical are not executed with -reuse
added more unit tests about variable values
Allow to substitute test variables with global values using $
New -vars option to override test vars with values in YAML file
fixed interpolation problems of new global values on non-overrided tests
Merge pull request #29 from Zentyal/jacalvo/upgrade-improvements

Jacalvo/upgrade improvements
Merge branch 'master' into rduran/windows-anste-slave

Conflicts:
	ChangeLog