--infer-rw should take no argument (#829)

This fixes --infer-rw to not expect an argument. After the annotations
refactor, no option was required, but some legacy code remained.

This also updates the test cases to be more correct and not specify an
option to --infer-rw.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>