Updated Jruby definition to version 1.7.4. Don't fail when java isn't available.

Signed-off-by: Daniel (dmilith) Dettlaff <dmilith@verknowsys.com>
Disabled Lftp definition on Linux (issue with readline)

Signed-off-by: Daniel (dmilith) Dettlaff <dmilith@verknowsys.com>