Added Travis configuration file.
Changed to install numpy/scipy with apt-get.
Removed debugging options.
Merge remote-tracking branch 'upstream/master' into placeholder

Conflicts:
	setup.cfg
Merge remote-tracking branch 'origin/placeholder' into fix-unit-tests
Fixed doctest.
Fixed failing doctests. Added staticmethod.

Added
-----

* Added staticmethod decorators to methods that do not alter the grid.
  This removes the need to create an "empty" grid, which is no longer
  possible.
Changed to not squeeze corner/neighbor arrays.

Changed
-------

* Do not squeeze arrays that return corner or neighbor nodes.