Update astropy_helpers to v0.4
Use ah_bootstrap.py from astropy-helpers v0.4
Aperture photometry returns a Table as output
Changing tests
Fix doc examples to get doctest pass
Change output column name, add versions to metadata
Adding FLOAT_CMP to doctests
Change back output column name
Updating start page example
Fixing broken link
Changing assert to assert_allclose
Replace deprecated param_dim with n_models
Update detect_sources docs
Merge pull request #109 from larrybradley/model_update

Replace deprecated param_dim with n_models
Minor docs modification
Changing column names to aperture_sum and aperture_sum_err
adding unit=None in cases when data has no unit
Simplify docs in scale_img
Removing ndarray conversions to keep input units
Ensure correct array dtype in centroid_com