Add ruby 2.x to travis testing
Fix some specs broken by 2.x's new rules

 * default utf-8 everywhere broke tests in lib/rex/text_spec that dealt
   with binary data
 * new protected rules
Fix respond_to specs for protected methods
Force msfconsole to use stdlib's readline with -L
Fix readline by mucking with load path
Better explanations
Move readline choice into a method
Remove the now-unnecessary -L
Land #4084, prep for Ruby 2.1