Merge pull request #502 from anodelman/vagrant-warnings

(QE-129) test harness reports vagrant warnings on box set up
(QE-90)  validate test systems have required packages/services before
testing.  First pass -  checks for curl and ntpdate, installs if missing
(QE-90) ivalidate test systems have required packages/services before
testing
Adds check_for_package and install_package to the dsl