drop 1.9.3 and 1.9.2 from travis.yml
use Module#prepend for Exception monkey patch
remove workaround for 1.9 broken local variable bug
remove 1.9.3 compatibility code
don't build on jruby, it has incomplete 2.0 support
Merge pull request #237 from charliesome/drop-1.9-support

Drop 1.9 support