Making gemspec executable.

Just a small improvement. By making gemspec executable and
using `#!/usr/bin/env gem build` as a shebang, you can just run
./artfully_ose.gemspec to get a new gem. Neat, huh :) ? It works
on OS X, unfortunately not on Linux due to differences in the env
implementation, but you can always run gem build manually.

Why?
Fair enough, I'm really responding to http://tiny.cc/a3ucuw I love
the company values you described in there and I'd be very interested
in talking to you whether we can help each other out.

Regarding the skills, even if I'm trying my best to stay humble, I have to
say, I have it all ;) I've been working with Ruby for over 5 years, I worked
for many start-ups as well as for big companies (like hacking VMware hacking
AMQP libraries there). I also have a lot of JS expertise. In any team I've
been, amongst the Ruby people, when it came down to JS, it was always me who
done/fixed whatever was necessary. Back in the days I've been making sure that
whatever app I was working on works in IE6. What a nightmare, but I've done it.

If you could be interested in talking to me (friendly advice: you should ;) ),
here's my CV: http://static.101ideas.cz/CV.html and I'd be happy to Skype or
chat or whatever.

Oh ... just so you know I'm based in the UK, I hope it isn't a problem? Also,
I'm not sure whether this is permanent-only, I'm a contractor (I don't have
a problem with working full-time though and contractor doesn't mean lazy or
not caring about the product, just so we're on the same page!).

Oh and here's my email address: "Y29udHJhY3RzQDEwMWlkZWFzLmN6\n" OK, I'm
cheating a little bit, but I'm sure you know how to decode that, right ;) ?

Cheers,

James
Merge pull request #4 from botanicus/master

Making gemspec executable