Spark-Connector：Compatible with spark2.2

[Nicole00]

1. develop nebula-spark-connector with spark 2.2， which means use SparkSQL's DataSource v1 to extend Nebula datasource.
2. nebula-spark-connector with spark 2.2 should be a dependent module in this repo.
3. make this product's name as neubla-spark-connector_2.2.

[handsonbao]

our partner pushi wants to transfer from Janus to Nebula. But they now use spark 2.2. It will be great if we can support as soon as possible.