reflow/url.py:
- trying out rest_framework_docs app that shows the REST api structure in a nice web interface

models.py:
- added get_channel_as_numpy method to Sample...may need to do this with a channel list???
- fix typo in sample_file variable (line 401)
- SampleParameterMap: make parameter and value_type optional,
      we will add a sampleparam map for each channel when a sample is loaded even if it isn't associated with a panel (not implemented yet)