Remove jruby and 1.9.3 from build matrix
Remove jruby and 1.9.3 from build matrix

The `mutant` gem specifies Ruby >= 2.0.0:

https://github.com/mbj/mutant/blob/75164ba31a9129fc16d27d7f4a3e741a90da4a12/mutant.gemspec#L24

will3216/feature,mgsnova/feature,will3216/feature,mgsnova/feature