move tip to utils so it can be picked up in the SDK

utils/tip/README.txt

 This is a rough experiment at more deeply integrating dart into a browser
 in order to simplify the dev experience.  It currently provides a simple
 playground for interactively messing around with dart code and an extension
 to chrome to automatically compile and run .dart files.  The goal is to
 provide the infrastructure to build browser extensions to chrome and other
 easily extensible browsers (such as FireFox) that will make it very easy to
 experiment with code and later full pages that incorporate the dart language.
 
 Note: All commands below must be run from the dart/frog directory.  They have
 not been hardened for launch from other locations.
 
 First, you need to build tip.js by hand - bootstrapping, ya'know.
 
 > ./frogsh --out=tip/tip.js --compile-only tip/tip.dart
 
 Then you need to start the local server:
 
 > ./frogsh tip/toss.dart
 
 Finally, navigate to the appropriate page in chrome:
 
 http://localhost:1337/frog/tip/tip.html
 
 You should see the editor.
 
 The part that sucks right now is that until we are properly bootstrapped, you
 will need to rebuild tip.js by hand (the first step above) in order to see
 changes.