<feature/sync-engine> update build config to not compile TestIos in debug and release #130
<feature/sync-engine> add prototypes to get updated and unchanged objects  #130
<feature/sync-engine> write sql scripts for sync engine #130
<feature/sync-engine> patch portable class lib to ios lib for intellisence
<feature/sync-engine> start implement sync tasks #130
<feature/sync-engine> fix covariance contravariance problems #130