Introduces rebin_cubeHDU function to image utils. Test case still to be done
Introduces cube option into rebin_cubeHDU
Adds unit test and makes minor changes to the rebin_cube_hdu function
Introduces new test cases for calc_footprint and block_reduce_hdu, improves the code for block_reduce_hdu in gammapy/image/utils.py
add 1d and 2D wstat
Add multi_gauss_psf_kernel function
Enable doctests via `python setup.py test`
Fix `coordinate_iau_format` doctest
Add `gammapy/data/tev_spectra/*` to `gammapy.data.get_package_data`.
Remove `aperphot` and `measure_bounding_box` functions.

This functionality is available in `photutils` and `scikit-image`.
Skip `healpix_to_image` doctest
Change `fermi_galacti_center` function to `FermiGalacticCenter` class
Add unit tests for FermiGalacticCenter
Improve sphinx formatting in install.rst
Fix doctest in introduction.rst
Add doctest skip directive to fit_sherpa.py (doesn't work)
Fix FermiGalacticCenter data example (use static methods)
Fix image.utils.coordinates doctest
Fix gaussian_sum_moments doctest
Skip doctest for MorphModelImageCreator