Refactoring Jsp + DefaultServlet + Resource Aliasing test cases
381521 Only set Vary header when content could be compressed
Merge remote-tracking branch 'origin/jetty-7' into jetty-8

Conflicts:
	tests/test-integration/src/test/java/org/eclipse/jetty/test/jsp/JspAndDefaultWithoutAliasesTest.java
temporarly remove test