Fix:
- urls should not be harcoded as they can change with time
- remove spaces around slashes in a string to be consistent with the next string also using slashes
- remove locale information from MDN link so as to allow locale detection, that document has translations available
- use only one version of 'Learn more' string in the template, without capitalization
Merge pull request #13 from pascalchevrel/Bug851143-l10n_string_fixes

Fix: