Performance improvements

Nothing new: only optimization and cleanup.

There is a Backward Compatibility Break if you used directly rules.json. Format has changed.
Use rules-legacy.json to benefit from the formatted data from version 1.0.x.

• builder now relies on grunt
• reduced the number of dependencies, all of them are devDependencies specific only
• reduced the filesize of rules.json (from 600K to less than 60K, it's about 21K gzipped)