Update Swt to 4.4

Title says it all. Note the versioning change in the swt gem, which now mirrors the actual SWT version :-)

First tests indicate that it works fine (at least with some of our big apps). Unfortunately it does not seem to get rid off #441 ...

Also, for me on Linux my scrollbar looks slightly awkward but no biggie (see screenie)

![screenshot from 2014-09-02 19 39 55](https://cloud.githubusercontent.com/assets/606517/4122830/8e0507b6-32c8-11e4-87a7-fe0652075fc3.png)

At first I thought it also introduced #879 but that seems to happen on master as well.

if you want try it out, please go ahead :-) (of course you will have to do bundle install to get the newest version)