Reducing kowalski dependence

[bfhealy]

As work continues on the first version of the scope PyPI package (see #514), it is worth considering the typical user and whether they will have access to the kowalski databases at Caltech. Currently, much of scope requires kowalski access to run, but there are several parts of the code that could theoretically stand independent from these databases. Going forward, it may add value to partially disentangle scope and kowalski without diluting the former too much.