Optional columns hidden if not in model

Reaction name, Reversible, Metabolite name, charge, compartment columns
not in table if not in model.
iaf1260-ac.csv reads w/ no errors

Upper bound contains the string "none". Reader now checks if value is
number, else sets default. Changed filters for column interface to
lower, upper so this model loads them into dropboxes. Added if lower
bound < 0 and reversible false, set lower bound to 0 to SBMLModelReader.
Resized progress bar to be symmetric.