Summary of changes:
6225cb4... Epel 7 with X 1.19 don't need vboxvideo_drv
https://forum (*)
1b96759... Update VBox to 5.1.30 (*)
472d0ce... Some updates on VirtualBox-guest-addition based on VirtualB (*)
d1f23de... fix typo in update script (*)
(*) This commit already existed in another branch; no separate mail sent