(r10k-#32) Support --verbose with no args

Cri uses the --verbose flag internally to display hidden commands. Since
a number of commands in 1.0 were deprecated, there has been this
alluring list of commands that are hidden, but using --verbose blows up
with the following:

    r10k: option requires an argument -- verbose

The --verbose flag previously required an argument rather than
arbitrarily pick a log level. To make --verbose work for displaying the
help, an arbitrary log level of 'info' was picked. This way, using
--help --verbose does what you would expect, rather than fail in a
rather obtuse manner.
(r10k-#32) Support --verbose on commands with no action

A number of commands have no implementation and mainly serve to act as
namespaces. When these commands are directly called, they return the
help to make use a bit more intuitive. Cri::Command#help takes an
optional :verbose option, and directly invoking it doesn't magically
transfer the argument from the command `run` block to the #help method.

To make sure that --verbose behaves as expected with these
implementationless commands, opts[:verbose] needs to be passed
explicitly.
Merge branch 'issue_32-verbose_help_flags'