Replace pickles in tests

[AaronDJohnson]

This issue was brought up in PR #159. Tests will break if anything about the file structure (for example an import moving from one file to another) or code being pickled (pulsar.py in enterprise) changes. These are not the intended targets of these tests. Instead, we should aim for more flexible alternatives such as small simulated par/tim files that are quick to read in that can be used in tests.