Set default language for phantomjs driver
Added phantomjs to documentation of available testbrowser
Use DesiredCapabilities instead Map for setting langauge
Fixed GroovyTest: the "default" version is not defined in Jenkins.

 Explicitly use the installed Groovy version in the script since it is not clear which is the "default" version.
Merge branch 'phantomjs_browser' of https://github.com/jenkins-acceptance-test-group/acceptance-test-harness

Conflicts:
	src/main/java/org/jenkinsci/test/acceptance/FallbackConfig.java
Merge branch 'master' of https://github.com/jenkinsci/acceptance-test-harness