milestones and research tags

[bblfish]

In #120 (comment) @timbl suggested that the issue brought up should be for version 2. So it would be useful to have some milestone tags.

It would also be useful to have a "research" label, on questions that would require further research so that the core platform can give the wider research community something to do. This would then allow future SoLiD workshops to have criteria for accepting relevant papers.

This would allow questions then to be reformulated in terms of research projects.