TestLink BUG-1890: Possibility to add attachment by using API

With the help of Francisco Mancardi I wrote a code that was merged into the TestLink repository trunk. Now you’re going to be able to upload attachments such as, for instance, test evidences to your TestLink :-). I hope you like it.

I decided to contribute with this code because I needed something similar for the TestLink Hudson plug-in. Hopefully the plug-in new version will be released before October.

Cheers