fix(Help Messages): fixes help message alignment when specific settin…

…gs are used on options

Prior to this commit setting `number_of_values(1)` and `multiple(true)` would cause the help
message alignment to be off. This commit fixes that.

Closes #760

src/args/arg_builder/option.rs

@@ -71,6 +71,9 @@ impl<'n, 'e> Display for OptBuilder<'n, 'e> {
                     try!(write!(f, " "));
                 }
             }
+            if self.is_set(ArgSettings::Multiple) && num == 1 {
+                try!(write!(f, "..."));
+            }
         } else {
             try!(write!(f,
                         "<{}>{}",