Merge pull request #20 from juancs/master

Added HTML and BODY tags to HTML content sent in urkund_create_temp_file
New Ajax script to verify receiver address
Basic validation of receiver - adds tick/cross to form
Validate receiver address using custom quickforms rule

We do this as the plagiarism api doesn't provide a hook for validation in the form.
Use core function for file reset.
Use same structure as parent class to remove strict standard warning.