Add user achievements

[TristanCacqueray]

trafficstars

• Define the login endpoint in protobuf
• Add achievements information on login
• Display badge on the user interface

| Name        | Query                          | Aggregations |
|-------------+--------------------------------+--------------|
| Contributor | state:merged and author:self   | project      |
| Maintainer  | state:merged and reviewer:self | project      |

Levels (based on the catalan numbers):

| Name       | Query      |
|------------+------------|
| Novice     | count>2    |
| Apprentice | count>5    |
| Seasoned   | count>14   |
| Competent  | count>42   |
| Proficient | count>132  |
| Expert     | count>429  |
| Prime      | count>1430 |

[morucci]

Maintainer could include the commenter:self ?

[TristanCacqueray]

Perhaps commenting is more of contributor task. I meant to associate the maintainer role for merged change event.