Update dev script to use CoffeeScript source

* Also, now running with forever and watching for source changes

dev

-npm start
+#!/bin/sh
+
+#
+# Development of Set itself is carried out in CoffeeScript.
+# (Please do not submit pull requests with changes to the genereated JavaScript.)
+#
+# If you just want to use set (not develop on it), please run:
+#
+# npm start
+#
+
+node_modules/forever/bin/forever -w -c coffee coffee/server.coffee