MAINT: update instrument test class

[jklenzing]

Updates syntax for instrument tests inherited from pysat as part of pysat/pysat#552.

• End-to-end instrument tests now iterate over a list of dict objects containing info to create an instrument
• pytest.mark statements updated accordingly
• package renamed as inst_loc

Currently failing on Travis since these updates are not in pysat develop-3, but passes locally when using the tst/inst_test_class_update branch of pysat.

[jklenzing]

Forgot to rerun this one earlier