Made whitespace consistent in System's loader error messages.

Least epic PR ever! Just a whitespace fix ;) 

Certain malformed module names would throw `Uncaught TypeError: Illegal module name"./../player"` but other patterns would throw `Uncaught TypeError: Illegal module name "./../player"` (notice the space after `name`).

Added the space, and added it to the tests as well. All 50 specs passing.

Edits were made to the files in `/lib`, and I ran `grunt` to build new versions in `/dist`. The README said not to edit `/dist`, but I noticed that a few other PRs had included the new build. Let me know if you'd prefer to build yourself, and I'll fix the commit to not include changes to `/dist`.

Thanks!