(MODULES-6831) Refactor install process to function
(MODULES-6831) Refactor install process to function

 - Wrap the installation process inside a single advanced function as
   Invoke-SimplifiedInstaller.

 - Simplify parameter handling by falling back to some defaults, when
   the parameters have not been specified by the user.

   With no user specified CertName, call Get-HostName
   With no user specified CACertContent, call Get-CA $Master

 - This call structure makes it easier to handle global errors and
   report correct JSON

puppetlabs/puppetlabs-bootstrap,puppetlabs/puppetlabs-bootstrap