Update and some new examples

* Update a mistake in ifconfig
* Add example for a SOCKS proxy in ssh
* Add an example for mounting a NFS dir in mount
* Add a description for git blame
* Add some examples in grep
* Add example for specifing an interface in dhclient
* Add a description for apt-get install
* Add some commands in apt-cache
* Add an example of pretty printing jsons using python
Added cheatsheets for markdown, ncat, and sqlmap.

Some cheatsheets that I created for a project for CIS4930, Ethical
Hacking and Penetration Testing. On request of the professor, I will be
sending a pull request with these cheatsheets.
Merge pull request #135 from Erethon/feature-cheatsheets-updates

Add some new examples
Merge pull request #136 from andrewjkerr/additional-cheatsheets

Added cheatsheets for markdown, ncat, and sqlmap.
Merge remote-tracking branch 'upstream/master'