Add additional Kepler/K2 names

[ajtribick]

Add Kepler, KOI, KIC, K2, EPIC and 2MASS identifiers from the NASA Exoplanet Archive keplernames and k2names tables.

For single star systems where planet letters could be determined unambiguously the addition is done automatically (first commit). For binaries and systems with warnings, I checked the files manually after the automated process finished.

[ajtribick]

Utility is at https://github.com/ajtribick/OecKeplerNamesUtility

[hannorein]

Oh wow. This is awesome! I won't check all the names and trust you completely here ;-)