#7 Implement Task Service to Push New Tasks Using JSON Format - added create task implementation incl. junit and integration test using json format

Copied and adapted basic JSON implementation from
https://github.com/mdanilkis/Mambu-APIs-Java/commit/e02981f07062635056d3
a2d71b736846b7771c92
Merge pull request #8 from mambu-gmbh/ISSUE-#7

#7 Implement Task Service to Push New Tasks Using JSON Format