Use Puppet 4's type system to deal with validation and remove dependency
on stdlib. Use the $::os fact to get Windows release version and remove
dependency on windowsfacts.

Some versions of .NET are in-place upgrades of others. Installation of
.NET 4.5, for example, will replace the 4.0 package. In order to
disallow Puppet from continuously trying to install .NET 4.0 in the
event dotnet resources for both 4.0 and 4.5 have been added to the
catalog, create a package=absent resource for each conflicting version.
This will cause the conflict to be caught when a catalog is compiled for
the node.

Some OSes have some versions of .NET built in and so do not need to have
it installed via package. It seems likely this was auto-detected based
on registry key presence/absence via exec previously. Because we're now
managing the package directly, we should be more explicit about whether
or not the package actually needs to be installed.

Regex adjustments to make it easier to read which versions support which
installation types.

Set gemfile to use PUPPET_GEM_VERSION and set default to 4.0

This is not a comprehensive test overhaul, but does update the
functional tests to work with the updated code.

Previously the dotnet define logic would attempt to install .NET 3.5 as
a feature on Server 2008. This was incorrect, as in Server 2008 .NET 3.5
was not available as a feature and needed the package installation.

Windows 7 does not install .NET as a package, nor does it have the
ServerManager module. Therefore provide an alternative means of managing
the feature via DISM.

The Puppet Exec resource uses the return code of command, unless, and
onlyif to determine success/failure or if action is necessary.
Previously, the onlyif in dotnet::install::feature would never exit with
a non-zero exit code, even if the Test-Path command returned a False
object. Return object and exit code are not the same thing.

This commit modifies the onlyif to ensure that if the Test-Path command
returns false a non-zero exit code will occur.

This will allow specification of different feature names. Necessary
specifically because the feature name to install .NET 3.5 on Server 2012
is not the same feature as to install 4.5.

The feature name for .NET 3.5 in Server 2012 is not AS-NET-Framework,
which we use as the default feature. This commit also updates the dotnet
type to attempt installation of the correct feature when 3.5 is
specified on Server 2012.

A custom fact 'dotnet4version' was created to pull specific
version from windows registry.  This is then used to determine
if desired .NET version has already been installed via non-msi
method (from windows update for example).  If desired version
is already installed, this prevents the downloading and attempted
installation of the package from occurring on each agent run.