Add a map for boundary-finding and Portland, ME to cities.txt

[llimllib]

• The largest body of this PR contains a full-screen map to make it easy to draw the boundaries of a metro area, and presents them in order for insertion into cities.txt. It uses leaflet, leaflet-draw, and mapquest tiles.
• The smaller bit is adding Portland, ME, largest city in the lovely state of Maine, to cities.txt
• I also removed trailing whitespace from cities.txt. I resisted the tempation to clean it up any further.
• I updated my gh-pages to show a demo of the boundary map

[migurski]

Whoa!

I’ll do Portland ME first, and circle around on the other stuff.

[llimllib]

No worries!

If I can fix anything, or you'd like me to re-arrange my PR to better suit your vision, just let me know.

[migurski]

I think it’s good, give me a day or two to properly digest.