Fixes TRAINVM-46: check hostname validity

See: https://tickets.puppetlabs.com/browse/PUP-677
Puppet fails when the hostname, and thus the username on the master
  is set to all numerals.
I decided to apply the test to advanced as well, since although we
  don't manage the ssh_authorized_keys it is possible that something
  that relies on executing a command as a user might fail if we set
  the hostname and the username with all numeric characters.
copy+paste fix
Disabling the caching of PE pacakges

yum-enterprise.puppetlabs.com is no longer needed for PE > 3
The puppetlabs yum repo, yum.puppetlabs.com now disabled by default
Merge pull request #184 from casharma/fix/remove-yum-enterprise

Disabling the caching of PE pacakges
update the regular expression for hostname validity
Fixes TRAINVM-56
Merge pull request #171 from casharma/bugfix/TRAINVM-46

Bugfix/trainvm 46
Additional steps needed to disable puppetlabs-enterprise-extras
Merge pull request #185 from casharma/more/disabling_enterprise_extras

Additional steps needed to disable puppetlabs-enterprise-extras
strip the MACAddress for interfaces
typo - not httpd, http
couple of minor fixes - use FileUtils, drop instance var
Edited README to add nokogiri gem
Merge pull request #187 from casharma/TRAINVM-8/macaddress

Trainvm 8/macaddress
fix a variable I missed earlier
Merge pull request #188 from casharma/followup/mac

fix a variable I missed earlier
Add a defined type to manage group class params

With this, we can set params on classes assigned to a group. I
anticipate using it to tune ActiveMQ when we get the testing
network built.
Merge pull request #189 from binford2k/wip/add_console_param_management

Add a defined type to manage group class params
Fixed to use the new rake task style
Merge pull request #190 from binford2k/wip/add_console_param_management

Fixed to use the new rake task style