bson-ruby's org.bson.ByteBuf clashes with Java driver

`bson-ruby` includes a jar file that defines a few classes in the org.bson package.

Java/Scala drivers define several classes in the org.bson package.

Running `mongo-ruby-driver` within JRuby Embed, along with the Java/Scala driver in the top-level JVM, leads to namespace clashes.

To test:

• Create simple Scala app with the Scala driver.
• Use JRuby Embed and include `mongo-ruby-driver` in your ScriptingContainer.
• Try loading any document from within the ScriptingContainer. The operation will fail if your classpath prefers the Java driver's version of org.bson.ByteBuf.

The solution is simple: https://github.com/fedenusy/bson-ruby/commit/d5160e41c256201a410ddc11aea590bb80131e1d