Fix to Pry::Command::Ls.error_list. Now non_mod_interrogatee is always false, so fix it.
Add spec to ls command. When 'ls -M instance' is called, exception should be raised.
Merge pull request #1072 from yui-knk/fix-ls-errorlist

Fix to Pry::Command::Ls.error_list. Now non_mod_interrogatee is always f...