Simplification of the dsl (#151)

with this change to DSL we're adding some helper methods and DSL simplifications 

- c(...) / p(...) - for consumer / producer
- for regex - e.g. $(anyUrl()) - insead of $(consumer(regex(url()))
- Added helper headers and media types
- Added helper http methods

fixes #149

tests/samples-messaging-camel/src/test/groovy/com/example/CamelMessagingApplicationSpec.groovy

@@ -94,7 +94,7 @@ class CamelMessagingApplicationSpec extends Specification {
 					])
 					messageHeaders {
 						header('sample', 'header')
-						header('Content-Type', 'application/json')
+
 					}
 				}
 				outputMessage {