checkDependency was failing quietly if it was called twice.  so if the first error was caught, then the second would not trip
resolves #471 - test was failing on minimal build
randn -> rand in quadrotor test, and silenced warning
removes affordance classes.  resolves #448
resolves #446
resolves #471 by adding a checkDependency for bullet in the MinDistanceConstraint.  closestDistance returns empty when bullet is not installed, which violates the constract of num_constraint=1
Merge pull request #472 from RussTedrake/minor

Minor fixes