Add jruby support

[zoras]

This PR allows suture to be installed on Jruby platform else following error occurs

❯ ruby -v                                                                                                                                        ⏎ ◼
jruby 9.1.2.0 (2.3.0) 2016-05-26 7357c8f Java HotSpot(TM) 64-Bit Server VM 25.25-b02 on 1.8.0_25-b17 [darwin-x86_64]

❯ gem install suture                             ◼
Fetching: sqlite3-1.3.11.gem (100%)
Building native extensions.  This could take a while...
ERROR:  Error installing suture:
  ERROR: Failed to build gem native extension.

    current directory: /Users/zoras/.rvm/gems/jruby-9.1.2.0/gems/sqlite3-1.3.11/ext/sqlite3
/Users/zoras/.rvm/rubies/jruby-9.1.2.0/bin/jruby -r ./siteconf20160927-32871-pky2oo.rb extconf.rb
NotImplementedError: C extensions are not supported
    <top> at /Users/zoras/.rvm/rubies/jruby-9.1.2.0/lib/ruby/stdlib/mkmf.rb:1
  require at org/jruby/RubyKernel.java:944
   (root) at /Users/zoras/.rvm/rubies/jruby-9.1.2.0/lib/ruby/stdlib/rubygems/core_ext/kernel_require.rb:1
    <top> at /Users/zoras/.rvm/rubies/jruby-9.1.2.0/lib/ruby/stdlib/rubygems/core_ext/kernel_require.rb:55

extconf failed, exit code 1

Gem files will remain installed in /Users/zoras/.rvm/gems/jruby-9.1.2.0/gems/sqlite3-1.3.11 for inspection.
Results logged to /Users/zoras/.rvm/gems/jruby-9.1.2.0/extensions/universal-java-1.8/2.3.0/sqlite3-1.3.11/gem_make.out

[searls]

Could you please also add jruby to the Travis yml file?

[searls]

Does the current failure in Travis make sense to you? I don't get it.

[zoras]

It's erroring out trying to start rails server for example/rails_app in jruby

[searls]

I just spent a little while looking through this and it looks like there's quite a lot of work left to be done, no?

Before this would work, wouldn't we need to implement a second SQLite wrapper based on RUBY_PLATFORM == "java", using either the jdbc-sqlite3 gem or the activerecord adapter if that'll save time.

[zoras]

Yes I agree, separate implementation of SQLite wrapper for jruby needs to be written.