Grunt buildsystem

As hinted in #8, I now created a suggestion for a build system, based on [Grunt](http://www.gruntjs.com) (& Node.js).

It provides three tasks right now, based on jshint, jsbeautify and uglifyjs . The readme.md has been extended to describe the process.

The caused changes are minimal:
* jshint is currently not in the default chain, since there are still too many errors reported
* jsbeautify only changed a bit of whitespace and indentation
* uglifyjs produced the same result, only comparisons where flipped ("x < y" became "y > x" at places)

If this pull request is accepted, I have the following further plan:
* Get jshint used; Get rid of the non-configurable warnings & integrated in compile chain, then make settings more strict on the further go
* Clearer project structure (separation between src, demo, lib)
* yuidoc task for documenting the public API
* Introduce CommonJS format (browserify); A CommonJS format helps regarding dependencies (jshint undeclared warnings) and would make the bits testable under Node.js
* Add a test framework

My goal in all of this is to make it easier for people to use and contribute to the library.