[JOSS review] Remove external licenses in NOTICE folder

[AdamRJensen]

I think it's quite unusual to include a folder with the licenses of dependencies.

One of the main reasons I'm against this is that it is a certainty that these licenses will be outdated. For example, the included pvlib license is no longer correct. pvlib does not do this, and given its affiliation with Sandia I do not think this is necessary here.

Perhaps @cwhanse can comment on this from a Sandia point of view?

[cwhanse]

I agree with @AdamRJensen we don't need to include license text for packages that are imported. Importing a module is use of that module, not redistribution. If we include a copy of the source code for a package, then we would need to preserve the license text.

[kbonney]

Addressed by #80. Resolution: deleted notice folder