Changing the way the amd module is exposed

Since this might be used in other places besidea require project,
I thought it might be handy to "expose" it in the same style as
jQuery or underscore or whatever. Doing that I had to change how
it was getting included in my AMD project.
Changing calculateElementWidth for old IE

In IE7 and IE8 (and maybe older, and maybe other browsers)
el.css('marginLeft') will return 'auto' instead of 0px. So I'm
checking to see if that value was returned, because parseInt will
return a NaN if we give it 'auto'. Also removing the margin in our
test fixture and updating tests.
merge conflict