Added metainspector gem

For processing a html page to get a title and description and possibly the images, when adding by url
removed the use of table to layout the file/url upload buttons, and reverted back to using ul/li
some initial prototyping of adding an upload url and providing a summary and applicable options
initial refactoring, reorganising and cleaning up of upload code and logic wrt to files and urls
updated VLN specific upload from tool and email methods to use new upload method
fixed some of the styling and javascript behaviour of the upload url/file toggle buttons
consolidated javascript for upload handling into javascript asset
some initial simple formatting of the url information for a website
some initial simple formatting of the file information for registering a URL to a file
added a spinner whilst waiting for url to be processed. Also added the spinner image as a CSS definition, and will update other uses of it to use this later
fix for websites that accept application/xml, and request the RestClient specificly requests HTML
minor UI tweak
fixed some code style
fix to displaying the size when unknown
some handling of the original filename, fetched from the content-disposition if available
handle unauthorized link with previewing URL
recognise and report method not allowed error
handle 404 whilst examining URL
fixes for tests, wrt 401,403,302,301 response codes when adding data by URL
fix for missing net/ftp, which is required in assets_common_extension but was defined somewhere else