bump and remove snapshot

Merge pull request #37 from mixpanel/jared-ms-updates

send millisecond time and update junit and json dependencies

Merge pull request #37 from mixpanel/jared-ms-updates

send millisecond time and update junit and json dependencies

Support for group analytics

Release 1.4.4

[maven-release-plugin] copy for tag mixpanel-java-1.4.3

[maven-release-plugin] copy for tag mixpanel-java-1.4.2

[maven-release-plugin] copy for tag mixpanel-java-1.4.1

[maven-release-plugin] copy for tag mixpanel-java-1.4.0