HSC survey

[SunilSimha]

Code to slurp in data from the HSC survey. The code currently queries the Wide field data alone although one could switch to the deeper fields using custom queries. This PR includes:

1. A new HSC_Survey class. Only slurps in catalogs currently. Includes the database photo-zs as well.
2. Accompanying unit test.
3. HSC Filter curves (atmosphere+instrument+filter).
4. CIGALE and EAZY expansions.

[bandersen441]

Looks good to me, and works well so far. Although it looks like one of the required checks isn't yet passing? astropydev?

[profxj]

merging