Updating README Maven version to 2.2.

Merge pull request influxdata#132 from antjori/IgnorePointNullValues

Fix for issue influxdata#117.

InfluxDB Java Client v2.0

Adopt Readme

[maven-release-plugin] copy for tag influxdb-java-1.5

[maven-release-plugin] copy for tag influxdb-java-1.4

[maven-release-plugin] copy for tag influxdb-java-1.3

[maven-release-plugin] copy for tag influxdb-java-1.2

[maven-release-plugin] copy for tag influxdb-java-1.1

[maven-release-plugin] copy for tag influxdb-java-1.0