fix test of test_mode, include 'ncurses'

The tests all complete successfully in JRuby only if I make 
sure rubygems is loaded by adding:

  require 'rubygems'

To the test code.

Currently there is a bug in JRuby's processing of RUBYOPT

  http://jira.codehaus.org/browse/JRUBY-4060

so just setting:

  export RUBYOPT=rubygems

doesn't solve the problem.

test/tc_highline.rb

@@ -412,7 +412,7 @@ def test_lists
   end
 
   def test_mode
-    assert(%w[Win32API termios stty].include?(HighLine::CHARACTER_MODE))
+    assert(%w[Win32API termios ncurses stty].include?(HighLine::CHARACTER_MODE))
   end
 
   class NameClass