Update the Postfix site URL
Merge pull request #20 from kipit/patch-1

Update the Postfix site URL
Add chapter `Installation`.
Merge pull request #21 from htgoebel/master

Add chapter `Installation`.
Fix reST-markup for `Local Variables` comment.
Add chapter `Getting Started`.
Merge pull request #22 from htgoebel/master

Add chapter `Getting Started`.