Integrate with Clearbit

[pranavrajs]

Allow users to connect their Clearbit accounts. When a contact is identified, query Clearbit and store the information about the user.

Acceptance criteria:

• Add Clearbit to the list of integration apps
• Allow users to set a Clearbit token installation wide.
• On contact updated event:
  • If user email is available, Query Clearbit with the email and update additional_attributes
• Display attributes on the contact details page