Add 'grailsApplication' var to resources.groovy to align with other artifacts.

Since all static holders are deprecated since Grails 1.4-M1 I was trying to access config values in resources.groovy
I tried with grailsApplication var as this is used in other artifacts.

Later I found out (http://grails.1312388.n4.nabble.com/1-4-M1-How-to-access-grailsApplication-config-in-resources-groovy-td3553500.html) that I should just use the 'application' var.

I think it would be better to align this that all artifacts use 'grailsApplication'.

For backwards compatibility it might be best to support both 'application' and 'grailsApplication' var in resources.groovy.