Made formchooser work

For issue37 and issue18

Now, after the user sign in, it will work like this:

• First, check if there is any existing form created by this user.
• If there is no existing form, the user will be led to the company info step/page.
• If there is at least one existing form, the user will see 2 options, "Continue Existing Application" and "Start New Application"
• For "Start New Application", the app will create a new empty form for the user and let the user fill up all required info.
• For "Continue Existing Application", the app will use the latest form for the user.
• Create new forms (organization, membership level, working groups etc.) when user chooses "Start New Application" and hits "Next/Submit" button
• When user chooses "Start New Application", the app won't do a GET API call to back end because there is no data, but will do so if user comes back from a later/further page so that the app can get the id for doing PUT API call to update the form.
• Prefill the form with existing data when user chooses "Continue Existing Application"
• Update existing forms (organization, membership level, working groups etc.) when user chooses "Continue Existing Application" and hits "Next" button,