fixing the markup in the js
adding markup changes to caption-filter
#1963526 improving the responsiveness of caption filter
#1963796 adding support for retina_images module
merging updates into 6.x-1.x dev
#1402056 Warning getimagesize failed to open stream in _caption_filter_get_width()
#1898986 - add js through hook_page_build() and not hook_init()
#1937616 - fixing php noticed associated with _caption_filter_get_width()