Merge pull request #4339 from scientificlinux/sl7

Update sl container for sl7 to current (build-date=20180510)

library/sl

@@ -8,7 +8,7 @@ Tags: 7, latest
 Architectures: amd64
 GitFetch: refs/heads/7
 Directory: sl7
-GitCommit: 07363f7d232403041802d04b811079229f3fefbd
+GitCommit: cc19070a8d75c826af21c28251d409b1463d747f
 
 # For the SL6 container
 Tags: 6