created a function for rule
created BooleanResponder
added string responder
fixing layout problem in example
added example for using boolean responder with ng-if
adding ngIf usage to example pages.
adding a basic responder to avoid test duplication
moving responisbility to call  to widtheventlistener, also refactored function names
added directive for src to be used by responsive-include and responsive-image.
some cleanup of things left in.
creating responsive-image before starting work on responsive-include
small change to error message
changed names of templates in include to match naming conventions
small fix to responder
updated doc and example
added simple example for using stringresponder with ngInclude.
added test for responder since it's documented to return class
merged readme