ui: user token creation through request/approval process

[mvidalgarcia]

ui

• [x] Create some fast mockups to discuss before starting with the actual implementation.
• [x] Prevent displaying the user token in the welcome page for social logged in users. Instead, display some message saying that social login requires verification and the token is in a "waiting" state and that administrator will contact him/her back once it's approved.
• [x] Show waiting/approved status in profile page
• [x] Handle 'revoked' case

server

• [x] Create a new endpoint to be called from the ui to create a user token and mark it as requested.
  1. Use User.request_access_token()
  2. Send email to reana administrators

Tightly related to https://github.com/reanahub/reana-server/issues/235

[tiborsimko]

Ad 2, we can do it for everybody, not only for social logins.

The message would go like:

Welcome to REANA!

It seems that this is your first login to REANA. In order to use the system,
you need to ask for an access token.

      [ Request token ]

After people click on the "Request token" button, we can show something like:

Welcome to REANA!

Your access token request has been forwarded to REANA administrators.

Action: requested access token
Date: YYYY-MM-DD HH:MM:SS
Status: pending

After admins approve the person, we can display the usual message:

Welcome to REANA!

Your access token is aaabbb111333.

It seems that you have not run any workflows yet.  Would you like 
to run a first reproducible analysis example? Please proceed
as follows:

    $ ssh lxplus 
    ...
    $ git clone
    ...
    $ reana-client run
    ...

P.S. For people using REANA from outside of CERN, we'd also have to point to pip install example, not only to ssh lxplus example, on how to get the reana-client CLI executable.

[mvidalgarcia]

Some mockups:

Before requesting token:

After requesting token: