Change formatting style for outputs, bump dependency versions.

* Use string.format rather than % for outputs
* Bump version number dependencies on numpy, astropy
* Check for luminosity distance being a quantity
Change cosmology mechanism, improve string repr of mbb_results

* Use getattr to grab the right cosmology instead of storing
  them all in a dictionary.  Adds mbb_results.cosmology
  property to access that.
* Improve __str__ formatter for mbb_result, printing out lambda_peak,
  dustmass, l_ir if computed.