attempt to fix occasional travis build failures (timeouts)
fix travis build
prevent travis running "./gradlew assemble"
refactor Travis build settings in gradle build
add .travis.yml for 2.3.x branch too
Merge branch '2.3.x' into 2.4.x

Conflicts:
	.travis.yml
	README.md
	build.gradle
Merge branch '2.4.x'

Conflicts:
	.travis.yml
	grails-test-suite-web/build.gradle