Minor fix: Added `scr/wrand.js` to rubber.html

Added a script tag for `scr/wrand.js` to rubber.html, for more working.  The `WRand.setSeed()` call within `SolarSystem.prototype.setBodies` dies elsewise.
Merge pull request #1 from capnslipp/master

Minor fix: Added `scr/wrand.js` to rubber.html