base.install and infiniband: Remove packages that are not in used in EL

openib and netcat-openbsd are packages that are not available in the ELs
distributions. Neither 6.5 or 7.0, hence they are removed.
base.install: Fix major version test

Due to the lack of space after '6' in the test, the latter always
returned false, provoking edeploy to try to install grub2 on EL6.5
deploy: Install python-apt package only in Debian like platform.

EL variant do not have a python-apt package, hence it makes no
sense to install them on those platforms.
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
Merge pull request #109 from enovance/centos_packages

Fixes inconsistency in 6.5 and 7.0 EL variants