Graylog2/graylog2-web-interface — pull request #103 by kesor (2012-12-06 14:26:09+00:00)
Title: Fix mongodb rejecting insert of second user because of unique indexes

Allow null values in ```users.remember_token``` and ```users.api_key```.

When a new user are created these values are null, first user is okay but the second user is rejected because of the unique indexes.

Sparse indexes keep uniqueness when the field (```remember_token``` or ```api_key```) appears in the document, but when these are null on insert then mongoid will not add them to the document at all - which is allowed by a sparse index.