Pull Request to reduce memory leak from issue #59

This pull request includes changes to vis.html and vis.js that reduce the use of Angular and increase the use of d3. Also, rather than doing lots of little watches per per/country, we now do just one big watch for all countries and one for all peers.

In my testing, this reduced the rate of memory leakage by about 25 to 1, but did not completely eliminate it.  Still, probably worth taking.

See issue #59.