1.1.20 (22/01/16)

• pre-maturely avoid Ruby frozen string literals coming at us ... ''.dup meh!
• allow to boot when RAILS_ROOT/public directory does not exist (closes #197)
• for better booter detection - export public path after working dir was changed
• ActionController::Base provides a method servlet_response to return the
  java.servlet_response rack env (#201)
• adjust jruby home dir fallback (for default $LOAD_PATH) correctly on 9K and --2.0
• servlet env should behave on fetch and [] like a Hash (nil value can be set)