Updated the check of the Yum Output Signature

[mlwood98]

I noted that the check_yum plugin began failing on all of my EL7 machines shortly after our latest patch cycle. I found this to be due to the output of the yum check-update command wrapping the lines of several updates and then counting them as two. I updated the check to allow for double the number of updates + 25 lines, thus allowing for a case where all output lines may be wrapped, plus the header info and enough space for a high number of repositories in the yum configuration to be listed at the beginning of the output. This change is working well in our environment.

[LorenzBischof]

We are using this plugin with Centos 7 VMs. What's preventing this from being merged?

[calestyo]

I'd guess this is the same issue than #23, though I couldn't reproduce that so far on my CentOS7 systems.

Could we move any further discussion to #23 please? Same questions to you guys, which exact distro, yum versions and debug output?