Gemify focuslight

Added focuslight command to start up.

You can start focuslight installed as a gem like this;

```
vagrant@precise64:~/focuslight$ rake build
focuslight 0.0.1 built to pkg/focuslight-0.0.1.gem.
vagrant@precise64:~/focuslight$ gem install ./pkg/focuslight-0.0.1.gem
Successfully installed focuslight-0.0.1
Parsing documentation for focuslight-0.0.1
1 gem installed
vagrant@precise64:~/focuslight$ focuslight
12:49:56 web.1     | started with pid 5260
12:49:56 worker1.1 | started with pid 5262
12:49:56 worker2.1 | started with pid 5263
12:49:56 web.1     | I, [2014-02-26T12:49:56.791714 #5261]  INFO -- : listening on addr=0.0.0.0:5125 fd=9
12:49:56 web.1     | I, [2014-02-26T12:49:56.791871 #5261]  INFO -- : worker=0 spawning...
12:49:56 web.1     | I, [2014-02-26T12:49:56.793173 #5261]  INFO -- : master process ready
12:49:56 web.1     | I, [2014-02-26T12:49:56.799574 #5271]  INFO -- : worker=0 spawned pid=5271
12:49:56 web.1     | I, [2014-02-26T12:49:56.799814 #5271]  INFO -- : Refreshing Gem list
12:49:57 web.1     | I, [2014-02-26T12:49:57.604955 #5271]  INFO -- : worker=0 ready 
```

I'm not sure where is the best place for the data directory. 
In this commit it is made in the $HOME/.focuslight/data directory.