utils.py:
- implemented PATCH-based function patch_sample_with_panel() to apply a panel to a sample...using requests which is sooo much nicer than httplib (will be switching the rest of the code soon)
- remove unnecessary print statement in post_sample()
- added _visit_pk as a filter field for get_samples()

apply_panel_to_samples.py:
- created example script for applying a panel to a sample