Update Sign Up Form

[nms377]

• added lib directory in client directory for the userReq.js file that holds the XHR request to add a user to the database
• set state to empty string values in handleSubmit function to clear the form when user submits data
• update database, action, and reducer to include confirm_password column to validate the data entered in both password fields match
• will work on validating the data passed into the form

resolves #59