Removed some unnecessary library references that caused problems for conda on OS X
Merge pull request #655 from peastman/paths

Removed some unnecessary library references that caused problems for conda on OS X
Fixed bug in Quantity.sum()
Merge pull request #656 from peastman/sum

Fixed bug in Quantity.sum()
Workaround to support GTX 980
Merge pull request #658 from peastman/980

Workaround to support GTX 980