#73 abbot.tester.swt.CTabItemTester addition

[Ricardo Garcia]

Let's try this again, somehow my attachment wasn't
included.

I created the CTabItemTester to help me test my UI
using abbot.swt. It works in my test framework and
thus I think is worthy of addition to the abbot.swt
framework with a bit more testing. I tried to
following the coding style of the other Tester classes
as closely as possible.

[Ricardo Garcia]