Updated README.md (install and run)

The instructions now link to background info about PMT and PCP, say what exactly to clone and then how to run the tools.
Update README.md
Updated README.md redux (install and run)

I have removed "npm install" from the instructions, as requested, but I haven't checked yet if the tools can then save etc.
Merge pull request #32 from cstrobbe/patch-1

Updated README.md (install and run)