Get rid of bundler inside jar

At first. Huge thank you for this feature! This is what I wanted for years in ruby ecosystem.

But I can't make it work as is.

```
 java -jar api.jar
01:37:36,523 [INFO ] org.projectodd.wunderboss  - Initializing application as ruby
Could not find rake-10.3.2 in any of the sources
Run `bundle install` to install missing gems.
Exception in thread "main" org.jruby.exceptions.RaiseException: (SystemExit) exit
	at org.jruby.RubyKernel.exit(org/jruby/RubyKernel.java:877)
	at org.jruby.RubyKernel.exit(org/jruby/RubyKernel.java:840)
	at RUBY.(root)(/var/folders/28/_36t5qdj65x37562tngrt_8m0000gp/T/wunderboss518836244026180736/jruby/lib/ruby/gems/shared/gems/bundler-1.6.2/lib/bundler/setup.rb:14)
	at org.jruby.RubyKernel.require(org/jruby/RubyKernel.java:1065)
	at RUBY.(root)(/var/folders/28/_36t5qdj65x37562tngrt_8m0000gp/T/wunderboss518836244026180736/jruby/lib/ruby/shared/rubygems/core_ext/kernel_require.rb:1)
	at RUBY.require(/var/folders/28/_36t5qdj65x37562tngrt_8m0000gp/T/wunderboss518836244026180736/jruby/lib/ruby/shared/rubygems/core_ext/kernel_require.rb:135)
```

When I googled for solution I found `--standalone` option which makes a bundle that can work without the Bundler runtime. This is another approach, but it works for me. No bundler, no such issues at all.