Add support for /proxy URLs.

Pencilcode will bounce requests for applications (as long as the referer
is also pencilcode.net) using the url /proxy/URL.

This allows applications to request cross-origin resources (such as images)
without security issues.  (For example, a proxied request will not have
access to domain-specific cookies, and it will not have access to any
private network.)
Add /proxy/ forwarding to dev server.
Add test for proxy functionality.
Merge pull request #69 from PencilCode/nginxproxy

Add support for /proxy URLs.
Bowercopy update to latest.
Add lib/keyboard.coffee
Keyboard extends Sprite

This way, a keyboard is just another Turtle that you can move around
on the screen just like any other turtle, for fun and nice visual
effects.
Speed up keyboard using canvas drawing.

Turtle drawing is slow, so this rewrite expresses the keyboard
drawing using raw canvas drawing.  It now preforms acceptably
well in Firefox.
Friendlier constructor for Keyboard
More muted colors.
Merge pull request #70 from PencilCode/keyboard

Add lib/keyboard.coffee
merge master
Fix proxy behavior for /proxy urls