JRuby Support

Curious if JRuby might be supported. Getting the following at the moment when attempting to install the gem by placing it in my Gemfile and running `bundle install`.

```
current directory: /Users/user/.rvm/gems/jruby-9.1.17.0@aryeh/gems/arg_scanner-0.3.0/ext/arg_scanner
/Users/user/.rvm/rubies/jruby-9.1.17.0/bin/jruby -r ./siteconf20190521-5756-1609kxo.rb extconf.rb
LoadError: no such file to load -- debase/ruby_core_source
require at org/jruby/RubyKernel.java:956
require at /Users/user/.rvm/rubies/jruby-9.1.17.0/lib/ruby/stdlib/rubygems/core_ext/kernel_require.rb:55
at extconf.rb:5
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.

Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/Users/user/.rvm/rubies/jruby-9.1.17.0/bin/jruby

extconf failed, exit code 1
```