ServiceHelper

This will be the initial draft version of our new backend. ```ServiceHelper``` class is created to be a middle layer between UI and background services (network and database stuff). Each entity in Taskworld will have it own ```ServiceHelper``` which extend from ```BaseServiceHelper``` class. Each database operation call will create a ```TransactionMessage``` and convert to URL endpoint with ```MessageConverter``` class.  
In this PR, I still not fully integrated with API stuff since I need the robospice stuff from @kittinunv-taskworld, but It should be covered the flow of transaction message in our new system. Feel free to comment and make sure to review this PR seriously( by check it out and run by yourself :) ).