Handle instructions with relative ip and immediate value

[kerrytazi]

Fixes #42

[Hpmason]

Sorry I've been busy with work, life and holidays. The code looks good, just one thing I tried to spend time on months ago, would you be able to create a unit test that shows that the original issue is resolve. I believe these changes fixes it, but I was not able to write a unit test that fails prior to these changes in the time I had to work on it.

If you or someone else can write that test, I would be comfortable merging this in.