Check if url for newznab provider being added starts with http|https, if not just add http://.
Abort adding provider if url is empty.
Trim leading and trailing spaces from the url for provider before any logic is ran on it.
Correct extension of default newznab provider image from .gif to .png.
Added some missing semicolons and cleaned up some trailing spaces in the js file.
Merge pull request #731 from thezoggy/dev-config_provider_js

Minor updates to the configProviders.js