Removing ScalaJ dependency

- Replacing import scalaj.collection.Imports._ to a native Scala implementation: import scala.collection.JavaConverters._
- Removing ScalaJ from the pom files
- Forcing casting when Java Types is required
  E.g.:
       java.util.Map[String, java.lang.Integer] instead of java.util.Map[String, Int]
Merge pull request #186 from sandroacoelho/byeScalaj

Removing ScalaJ dependency

Fixes #118 by making it obsolete.