Update .travis.yml
kdl_typekit: disabled tests if CATKIN_ENABLE_TESTING is false

CMake Error at /opt/ros/hydro/share/catkin/cmake/test/tests.cmake:17 (message):
  catkin_add_gtest() is not available when tests are not enabled.  The CMake
  code should only use it inside a conditional block which checks that
  testing is enabled:

  if(CATKIN_ENABLE_TESTING)

    catkin_add_gtest(...)

  endif()

Call Stack (most recent call first):
  test/CMakeLists.txt:7 (catkin_add_gtest)
Reverted orocos_kdl package renaming

This commit partially reverts
* "updating dependencies to use updated kdl package names, note that there are some external deps like kdl_conversions which still rely on 'orocos_kdl' instead of 'kdl', testing needed" (78269bea7b7a07fff8e282a1e2dcf07c0be671a2)
* "fixing target link libraries for kdl" (53a8a79498528633271c179db01c004381c4203f)
* "fixing deps" (3d3f929d5b49823d4438157ed581414fa05be10a)
* "Adding appropriate deps" (01f498fa379d65c8e1d7bd63f662b3b256a3c24e)
Merge remote-tracking branch 'jhu-lcsr-forks/master' into hydro-devel

Conflicts:
	kdl_typekit/CMakeLists.txt