Add the pick() function

Add the pick() function

This function is similar to a coalesce function in SQL in that it will
return
the first value in a list of values that is not undefined or an empty
string
(two things in Puppet that will return a boolean false value).
Typically,
this function is used to check for a value in the Puppet
Dashboard/Enterprise
Console, and failover to a default value like the following:

  $real_jenkins_version = pick($::jenkins_version, '1.449')

The value of $real_jenkins_version will first look for a top-scope
variable
called 'jenkins_version' (note that parameters set in the Puppet
Dashboard/
Enterprise Console are brought into Puppet as top-scope variables), and,
failing that, will use a default value of 1.449.