Fix a naming conflict jrubyc can introduce in generated java.

A ruby argument named 'result' will conflict with the stack local used for the return value: both will become 'ruby_result' in java.  Namespace arguments away from this by prefixing them with 'ruby_arg_' instead of merely 'ruby_'.

See #812
add the latest gems version in pom file
Merge remote-tracking branch 'github/master'