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

cheatsheets/git

@@ -26,6 +26,9 @@ git push git@github.com:username/project.git
 # To delete the branch "branch_name"
 git branch -D branch_name
 
+# To see who commited which line in a file
+git blame filename
+
 # To sync a fork with the master repo:
 git remote add upstream git@github.com:name/repo.git    # Set a new repo
 git remote -v                                           # Confirm new remote repo