[DOC] Updates to README
[DOC] Updates to README

* Better instructions on setting attributes
* Added note on installing latest Chef Omnibus via Vagrant::Shell provisioner to README
* Added link to the Chef Solo tutorial
* Added instructions on using Berkshelf Vagrant integration
* Added info on tests
* Added link to contributors

gilt/cookbook-elasticsearch,vacay/vcy-elasticsearch,vacay/vcy-elasticsearch,spuder/cookbook-elasticsearch,bavardage/cookbook-elasticsearch,nbudin/cookbook-elasticsearch,michaeld/elasticsearch-cookbook,gilt/cookbook-elasticsearch,zzugg/cookbook-elasticsearch,nbudin/cookbook-elasticsearch,spuder/cookbook-elasticsearch,gouketsu/cookbook-elasticsearch,spuder/cookbook-elasticsearch,zzugg/cookbook-elasticsearch,gouketsu/cookbook-elasticsearch,GemHQ/cookbook-elasticsearch,gilt/cookbook-elasticsearch,zzugg/cookbook-elasticsearch,nbudin/cookbook-elasticsearch,paulczar/cookbook-elasticsearch,gouketsu/cookbook-elasticsearch,vacay/vcy-elasticsearch