fixed spelling of splittable header utility
added test for mutable http servlet request for splittable logic
updated header splitting test for response header splitting
B-56167 fixing broken spock tests due to gdeproxy upgrade
Merge branch 'Bug-fix-header-splitting-logic' of github.com:rackerlabs/repose into bug-fix-branch
Merge pull request #728 from malconis/Bug-fix-header-splitting-logic

Bug fix header splitting logic