exclusive bids now supported and tested
added a namespace specifically for solver testing
exchng_tsts -> ex_tsts
made greedy algorithm a little simpler for exclusive arcs
updated exclusivity adjustment. this bug wasn't evident (or testable) because capacity-constraints will cause tomatch < remain which then will by definition be tomatch < excl_val of arc. all tests pass and alls well.
removed ex_tsts namespace. we can reintroduce if needed later
Merge branch 'exclusivity' of https://github.com/gidden/cyclus into gidden-exclusivity