spec/interception_spec.rb: pend the test of division by 0 on Rubinius

HI,

This patch offers the comfortable screen which is errorless on Travis-CI. 

It passes along all the tests at present. 
Here are the result of [my local environments](https://gist.github.com/ygotoh/df7d24f86b82b72f73c6) and [Travis-CI's](https://travis-ci.org/ygotoh/interception/builds/20267443).

regards,