def _plugin_constant
      @_plugin_constant ||= Guard.constants.detect do |c|
        c.to_s.casecmp(_constant_name.downcase).zero?
      end
    end
def _plugin_constant
      @_plugin_constant ||= Guard.constants.detect do |c|
        c.to_s.casecmp(_constant_name.downcase).zero?
      end
    end
Returns the constant for the current plugin.

 @example Returns the constant for a plugin
   > Guard::PluginUtil.new('rspec').send(:_plugin_constant)
   => Guard::RSpec