Feature/todoapp implementation hot fixes

[nikolay-vasilev-prime]

This PR is addressing the discussed comments in the Todoapp implementation.

It covers the following:

• Added a maxLines attribute to todo's description. This will allow the list and the details to show different number of lines of the details.
• In the todo local data source the naming of the key used for the share preferences is changed.
• Removed the commented code in places it was found.
• Changed the manage event name to be update.
• Perform a check if a subject isn't closed yet before closing it.
• Added error, loading and retry widgets in todo details page.