test Spring Boot and Ratpack Groovy DSL integration
add support for {@code ... } in javadoc code snippets
switch context classloader when executing javadoc code snippets
Add Spring Boot java code example to javadoc
add Spring Boot Ratpack Groovy DSL example to javadoc
remove tabs from indent
Merge remote-tracking branch 'lhotari/spring-boot-tests-pr'

Conflicts:
	ratpack-manual/src/test/groovy/ratpack/manual/snippets/extractor/JavadocSnippetExtractor.groovy