a test for check_endian
tests to make sure check_endian = off leaves data untouched
add bottleneck installation to travis
skip bottleneck tests if bottleneck not imported
change version of bottleneck to install
fix a ridiculously silly bug in which the computed result wasn't
returned
Merge pull request #66 from keflavich/issue66

check_endian code in _get_filled_data is buggy
cube should preserve the input header, since it almost certainly
contains important metadata about the origin of the data, etc.
track header around