Statements endpoint is timing out on items with many statements

[stuppie]

Statements endpoint is timing out on certain items: http://garbanzo.sulab.org/statements/?c=wd%3AQ12206
Need to paginate statements queries:
https://github.com/SuLab/garbanzo/blob/master/lookup.py#L299
https://github.com/SuLab/garbanzo/blob/master/lookup.py#L263

I might have some trouble with the time outs. I cannot make sure the result is globally sorted without retrieving the whole thing. It will be sorted when requesting the next page, but if you change a parameter, it might change the order "globally"

[stuppie]

@RichardBruskiewich
This particular example works now. Diabetes is in a couple thousand statements and runs in about a second now.
0a7b5e8

It does not solve the problem for enormous items though, for example, this still fails when you query for all statements with "gene"
http://garbanzo.sulab.org/statements/?c=wd:Q7187