Remove placeholder options specs, refs #118.
Allow integer rulers to be turned off at cmd line

Rulers that take an integer option did not accept 'off' or 'false' at
the command line, essentially meaning that they could only be disabled
through config.

Refs #117, #118.
Mark other options that take a NUMBER as integers.
Merge pull request #141 from acrmp/cli-allow-options-off

Allow integer rulers to be turned off at cmd line