Scanner input, .toUpperCase(), .replaceAll

Changed scanner.next to scanner.nextLine
Moved .toUpperCase from main "passkey" and "message" Strings to
EncryptionMethod class, encryptionTablet method "key" and "message"
Strings.
Added .replaceAll("[^a-zA-Z]+", "") to encryptionTablet method "key" and
"message" Strings.