Coding TimestampVector.java for Phase 1

Completed the missing parts of the implementation of TimestampVector.java
required for Phase 1 of the project. For this implemented the following
function:

updateTimestamp()
updateMax()
mergeMin()
equals()

As well as some small modifications in the rest of the code.
With these previous commits Phase 1 should be ready to be tested.
That's how you (don't) do TDD :-)