Add new endpoint: /count

[pepijnvanleeuwen]

GET /count should return the following information for current user:

• Amount of /actions
  • Amount of successful actions per device¹
  • Amount of invalid actions per device¹
• Amount of /conditions
• Amount of /devices
• Amount of /logs

GET /count/:endpoint should return the count for that specific endpoint. POST, PUT and DELETE are not allowed.

¹ if available.