Parametrized issue search
As a user I want to be able to search issues with a parameters, including AN, OR and NOT.
This Addressing things like a negative filter: "The first of these is what I’d call “negative filter”. Let’s say I want to see all issues that are labeled with backend and is explicitly not labeled as discussion. " http://christopher.rasch-olsen.no/final-thoughs-on-gitlab
This should work similar to https://help.github.com/articles/searching-issues/
Anytime you search it should be reflected in the URL so you can save the search, solving the use case of https://gitlab.com/gitlab-org/gitlab-ce/issues/18492
This functionality is something people need to switch from JIRA, for example the Mattermost team.