vcs: Remove all mention of use of -ve revision numbering. The introduction seems forced. It's a neat trick, but doesn't fit into the flow of things. Now introducing revision numbering with the need to take diffs between particular commits. Also mention -v and -l parameters to the log command.

vcs: Change email id to fossee from gmail.

vcs: Minor fixes to handout. 1. Made madhu's commit shorter to fit in one line. 2. Change Author details to have just the Name. 3. Change some punctuation.