ssh: Add aliases to hosts

Add aliases so that I can type short ssh commands.

This also has the benefit that I can lookup in my own files how the
`Hostname` option is called (I am always unsure if it is not `Host`).

.ssh/config

@@ -4,10 +4,13 @@ Host *
 	AddKeysToAgent yes
 	IdentitiesOnly yes
 
-Host aur.archlinux.org
+Host aur.archlinux.org aur
+	Hostname aur.archlinux.org
 	IdentityFile ~/.ssh/aur-druckdev
 	User aur
-Host github.com
+Host github.com github
+	Hostname github.com
 	IdentityFile ~/.ssh/github-druckdev
-Host gitlab.com
+Host gitlab.com gitlab
+	Hostname gitlab.com
 	IdentityFile ~/.ssh/gitlab-druckdev