Tell people not to be the BOFH.

This is a start to the "how not to be a sysadmin" section. I've tried to
achieve some balance between useful guidance and preaching.
content for airco, security in datacenters

Filled some content for review
added a new top level learning topic
added learning to break stuff out of soft_skills. Let's see if it worked.
fixed some quoting issues
fixed some quoting issues
Merge remote-tracking branch 'upstream/master' into learning
deleting learning from soft_skills
added some stuff on CBA in soft_skills
Merge pull request #79 from unpixie/learning

Learning
adding lots of stuff for rpm and deb package management
typo
improving the front page introduction, driving users straight into the careers section
fixing ref
Merge pull request #76 from avleen/index

improving the front page introduction, driving users straight into the c...
Merge pull request #80 from avleen/package_management

Package management
putting another pro-tip, mostly familiarizing myself with the process and making sure I'm doing it right.
formatting change
Merge pull request #83 from Sheeri/master

Added a pro-tip on databases 101
Added screen usage