[WIP] Test table api

Unfinished. Commit to get a review on changes I made to the Table constructor. For some reason types were not automatically being inferred from the call to discover(data) regardless of the kind of data. I could probably simplify this more by modifying the conditionals above the statement that I added. Relatively simply fix. 
I suggest that we just use global values like this (or local values if they're only used a couple of times).  I think that fixtures should be used when significant setup-teardown is required.  Thoughts on this approach @cpcloud ?