update ripienaar/concat -> puppetlabs/concat
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
Stop deleting the cached PE installer
Merge pull request #182 from casharma/fix/cached-installer

Stop deleting the cached PE installer
Updating the PE version and CentOS version.
Merge pull request #183 from klynton/upgrade/pe/centos

Updating the PE version and CentOS version.
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
Add fundamentals::environment user config class

This removes the shell & editor configuration from the
bootstrap module and moves it to a configuration exercise for the
fundamentals course. The exercise allows the student to choose their
favorite shell & editor.

This configures syntax highlighting, etc for editors and sets up useful
aliases for shells. The chosen shell & editor is configured as default.

This may mean that we'll need to add it back for the Learning VM.

The class accepts two parameters:

* `editor`: accepts emacs/vim/nano
* `shell`: accepts bash/zsh
cleanup

* the `in` keyword doesn't like undef as a lvalue
* fail instead of just warning
refactored to new module

* Moved this to its own module so that bootstrap & all courses can use it
* Added declaration to bootstrap so the Learning VM is configured
didn't mean to update the class signature
strip the MACAddress for interfaces
typo - not httpd, http