upload_preview 5.x-1.3

Clean up the code a little. Fix minor issues that coder found.
#337839: Dot at the end of url by KKaefer - Update wording to be cleaner.
#179378: Attempt to assign property of non-object in by davidwhthomas - Attempt to assign property of non-object in
#210647: make preview image be a link to original image by stella - make preview image be a link to original image
#337839: Dot at the end of url by seaji - Minor text fix that could cause some people issues.
Added class names to upload table. Patch by urbanfalcon (with modifications)
Implemented #109253: Preview also in the view page
#118739: Should not alter form if upload is disabled for content type: Should not alter form if upload is disabled for content type
#121762: Private files not fully supported : "upload_preview_file_download" missing: Private file support by toeofdestiny
Other Minor fixes.