1.1.0

Changes to the build setup to support Spark 2.2.x to 2.4.x and 3.0.x. There now is one maven release available per Spark version:

• spark-3.0-scala-2.12
• spark-2.4-scala-2.11
• spark-2.3-scala-2.11
• spark-2.2-scala-2.11