(QENG-608) Check_for_package method should not use which command

- properly differentiate between packages and commands
- check_for_package updated to check for the given package name using
  the correct package manager per OS
- added check_for_command, which uses 'which' to determine if a command
  is currently available
- added spec test coverage for check_for_package
(QENG-714/QENG-686) use all junit tags available for beaker xml output...

... provide local xslt for viewing beaker xml output

- switch over to nokogiri (cleaner, easier)
- add logs to system-out tag
- add tag for time that each test suite takes to execute
- add property tags for each beaker option
- add junit.xsl stylesheet to interpret test results
Merge pull request #293 from anodelman/junit

(QENG-714) use all junit tags available for beaker xml output
Merge pull request #229 from anodelman/pkg-vs-cmd

(QENG-608) Check_for_package method should not use which command