[ENHANCEMENT] Let challenger know they submit the wrong language or file

[misslame]

When a submission fails, let them know if they selected the wrong language or file if they do not match

[joshgarde]

If it can detect if a file isn't the correct language, why don't we just auto-detect the language in the first place?

[misslame]

Correction on title: have a message for when their submission fails that to check their syntax & selected language matches their file.