Only index ordinals if --index-ordinals is passed

[casey]

Some concerns with leaving this stuff in place behind a flag:

• extra subcommands in help (find, list, info)
• updater becomes a little more complicated (not incredibly bad though)
• have to maintain and test two configurations (for example, just have tests that exercise error messages when flag is not passed)

jk who cares, we can deal with those problems if and when they come up