Adding install instructions for homebrew

docs/source/install.rst

@@ -35,6 +35,26 @@ start Gandalf and git-daemon using upstart:
 
     $ sudo start git-daemon
     $ sudo start gandalf-server
+
+Install from Homebrew
+=====================
+
+You can install Gandalf server from homebrew, but first you need to add the `tsuru-taps
+<https://github.com/tsuru/homebrew-tsuru>`_:
+
+.. highlight:: bash
+
+::
+
+    $ brew tap tsuru/homebrew-tsuru
+
+Then, install the gandalf formula:
+
+.. highlight:: bash
+
+::
+
+    $ brew install gandalf
 
 Installing from pre-built binaries
 ==================================