mutli gauss class, effective area class and irf info script
Added test data for ARF and PSF
ARF and PSF tests
Changed pyfact to use new arf class
Merge pull request #142 from adonath/psf_analytical_class

Add PSF and ARF class and gp-irf-info script
Add gammapy/utils/array.py and fix test error in gammapy/irf
Adds initial predicted counts cube script
Adds unit test outline (incomplete)
Adds demonstration script to gammapy-examples
update
Fixes compatability issue with gammapy-datasets
update
Add energy_bin_centers_log_spacing utility function
Update npred computation and example with Ellis's latest version
Fix effective area test
Implement spectral cube coordinate and solid angle image methods
Merge pull request #149 from cdeil/fix_effective_area_test

Fix effective area test
Continue implementation of spectral cube npred computation
Merge pull request #150 from cdeil/npred_cube_fixes

Npred cube fixes
Uncomment checksum assert in IRF tests