When a node has puppet run for the first time, shorewall may not be
installed. In that case there are a few problems that appear in puppet4:

1. Warning: Facter: Could not retrieve fact='shorewall_major_version', resolution='<anonymous>': undefined method `split' for nil:NilClass

This is because running 'shorewall version' fails and so results in a
nil, and the split cannot be done on a nil. That is solved by first
running the 'shorewall version' and setting a variable. If that variable
is not nil, then we can split off of that

2. Error: Could not retrieve catalog from remote server: Error 500 on
SERVER: Server Error: Evaluation Error: Error while evaluating a
Resource Statement, Evaluation Error: Error while evaluating a Function
Call, 'versioncmp' parameter 'a' expects a String value, got Undef

This happens because the shorewall_version is set to Undef, but we need
to have it set to a String. So we set the variable to '-1' if it is not
installed.