Merge pull request #4 from juanda95/master

Fixed NullPointerException when used in Android
[maven-release-plugin] prepare release ubidots-java-1.6.3
[maven-release-plugin] prepare for next development iteration
Merge pull request #5 from juanda95/master

Adding usage by token and updating to work with API v1.6
Merge remote-tracking branch 'upstream/master'