base: Install the proper package according to CODENAME_MAJOR

Based on the EL version, 6.x or 7.x, packages have a different name
 or do exist in one version but not the other.

In 6.5 proper packages name are : man and grub

In 7.0 proper packages name are : man-db and grub2

Also in 7.0, the following packages do not exit anymore :

 * module-init-tools
 * upstart
 * vconfig

In EL variants the following packages never existed :

 * python-apt