Added bower and grunt json files

I've recently started to use bower and grunt to manage the use of my third party javascript files.
But this repo caused me a problem.

Your validate.min JS file states in the comments it was at v1.2.0 however the most recent tag was 1.0.2
When installing via bower I was getting 1.0.2 not the goodness of 1.2

I've included a component.json file with the correct data for bower to read. Having this file in your repo will also allow you to submit it to the bower package manager for easy install for other developers. Right now I have to install validate.js via a long git URL instead of a nice short name.
In addition I've tagged that commit as v.1.2.0

I've also added a grunt config file with the default task to minify validate.js to validate.min.js when running the grunt command.