Add jruby-1.7.17

http://www.jruby.org/2014/12/09/jruby-1-7-17

Highlights:
  56 issues fixed for 1.7.17
  native crypt()
  Fixed bad encoding of string interpolated within backticks
  popen2+ now works properly with env hash
  improvements to align MRI and JRuby FFI
  updated stdlib to 1.9.3p392 (+ rexml security fixes)
  tzdata updated