Update changes for EL7 and some bug fixes.

First commit fixes apparent bug on return type of exec(). The current Facter (2.0.1) returns a String, but the rest of the code expects an array. I just split the output into an array at the newlines. 

Second commit fixes (possible?) changes in nmcli. On EL7 and FC19 (and 20), the syntax is as shown. There may be a way to remain backward compatible, but I'm somewhat new to Puppet, Facter, and Ruby. I'm not sure the typical way to handle that.

My nmcli version is: 
`nmcli tool, version 0.9.9.1-26.git20140326.4dba720.el7_0`