Drag & Drop implemented
- Allows dropping text files in the TESTAREA
- FileReader API to read & extract file content

Signed-off-by: Soumya Deb <debloper@gmail.com>
Process only JSON input
- Echos if the input is JSON
- If the input is not JSON, shows error

Signed-off-by: Soumya Deb <debloper@gmail.com>