Add cmake to ZoneMinder

After a while working on this, i believe its ready.
One of my objectives for this was not to modify ZoneMinder in anyway, in order not to break anything. So as you can see, excluding the .travis.yml file, 16 new files are added, but 0 are modified and 0 are deleted.

Please all take a look at the INSTALL, to learn about building ZoneMinder with cmake.