Added numpy as requirement to build docs.
Added numpy as requirement to build docs.

chapel-lang/pychapel,russel/pychapel,russel/pychapel,safl/pychapel,safl/pychapel,chapel-lang/pychapel,chapel-lang/pychapel,russel/pychapel,safl/pychapel,safl/pychapel