Add __all__ to detection modules
Don't import detection.morphology and utils.scale_img in the top-level
namespace.

(they are lower-level and fewer top-level things means it's simpler
for the end-user.)
Fix sphinx warnings in docstrings in findstars.py
Re-organise docs a bit and get rid of Sphinx warnings
Set intersphinx_mapping to include scikit-image and astropy dev
Merge pull request #1 from cdeil/findobj-docs-warnings

Fix Sphinx docs warnings