Register baby functionality, Added functionality to queue API request to make app work offline

Closes #45 (closed), #46 (closed)

Tasks Done

• Baby able to get registered using app & their data is stored using api in DHIS2.
• This feature works offline also, data is synced when user is online next time
• Created a refresh bloc for state management
• Added Snackbars for showing info related to syncing
• stored the list in hive storage

Screenshot of snackbar message

syncing data with dhis2 snackbar message	data synced snackbar message