Make grails-web-sitemesh optional due to GroovyPageLayoutFinder being required by ResponseRenderer trait.

[codeconsole]

Unfortunately GroovyPageLayoutFinder is coupled to ResponseRenderer

and because it is a trait, changing it in any way would break any controller in a previously compiled plugin.

So basically, we are stuck with this dependency which will be resolved if either the grails sitemesh 2 or sitemesh 3 plugin is installed. Sitemesh 2 was made a transitive dependency of the org.grails.plugins:gsp because the plugin is responsible for configuring GroovyPageLayoutFinder.

This pull request makes all grails-web-sitemesh dependencies optional since they will be resolved by org.grails.plugins:gsp

[codeconsole]

@puneetbehl I will take a look.
the tests fail because org/grails/web/sitemesh/GroovyPageLayoutFinder is not in the class path. This is what was happening before with the other tests.

GroovyPageLayoutFinder is part of grails-web-sitemesh which is a transitive dependency of grails:plugins:gsp which is what injects groovyPageLayoutFinder. I believe it is the RestRederer trait that is causing the issue. I have just been adding grails-web-sitemesh as a test dependecy because the assumption is that grails-web-sitemesh will resolve automatically due to any grails app needing the grails:plugins:gsp dependency. Is there a situation you know of where a specific type of grails app will not have the grails:plugins:gsp plugin installed?