A tweak to make flags with default values act as switches when passed without args

[kbrock]

When a script is configured with:

opts = Trollop::options do
  opts :argwithdefault, "An Argument w/ a default", :default => "default value"
end

Then trying:

command --arg-with-default

Seems like we should get the default value rather than an error.

via gitorius

[kbrock]

default_string goes in there whether we have params << [opts[:default]] or next
unfortunately, opts[:argd_given] doesn't get populated.

feels like there should be a way to take the default without populating the params.

---

Need to digest more to ensurethe underlying meaning of "#{param}_given" is not modified here.
It means the user supplied a value. But if the user says "yea, yea. Just use the default value," then I guess this is the user giving the value.

[coveralls]

Coverage increased (+0.06%) when pulling 42b6912 on kbrock:default_with_switch into 1b132c1 on ManageIQ:master.