<feature/sync-engine> add server time stamp for all domain objects #130
<feature/sync-engine> add classes for sync issue #130
<feature/sync-engine> add IsSynchronized to all domain objects to track they synchronization #130
<feature/sync-engine> we must receive updated timestamp from server #130
<feature/sync-engine> sync requests have identifier for atomicity #130
<feature/sync-engine> Start implement sync engine. not tested now #130
<feature/sync-engine> add monotouch nunit project to test sqlite queries #130
<feature/sync-engine> start implement sqlite tests #130
<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
implemented singatures of all new RestStores #130
merged
<feature/sync-engine> start implement challengeAttempt storage #130
<feature/sync-engine> normalize domain logic #130
<feature/sync-engine> add dependency to challenge service #130
<feature/sync-engine> add storages to domain objects #130