Update versions for 2.4.3

To be able to create a new Grails Maven project using 2.4.3, I updated Grails version from 2.4.0.RC1 to 2.4.3 and some plugin dependencies :
* tomcat plugin from 7.0.52.1 to 7.0.55
* hibernate4 plugin from 4.3.5.2 to 4.3.5.5
* scaffolding plugin from 2.1.0 to 2.1.2
* asset-pipeline plugin from 1.8.7 to 1.9.9
* cache plugin from 1.1.3 to 1.1.8