Added Flash pop up feature

[abhinav5481]

Issue #2

I have created a system for pop using Flash. This feature is added in signin, signup, product sell & contact form. This would update the user regarding the request/response status.

The preview would look something like this

• For Signup

  If a user already exists this would show up a pop-up

On successful signup, the user would be redirected to the signing page with a pop-up

• For Signin

  After entering the correct credentials, the user would be redirected to home page with a message

• For Product Sell Form

  The error message would be shown on the same form as

After Successful submission of the product form, the user will get redirected to the profile page with a pop-up message

• For Contactus Page

  After Submission of a query, a message would pop-up

All the pop-up messages would last for 2 seconds. I have put up comments wherever required. Please review my code and let me know if any further changes are required.

[JINDAL-JJ]

@abhinav5481 update Contributions.md wrt your contribution.