Updated translations for 4.1.1
Use string for error code & enforce type safety to prevent crash
Merge pull request #1798 from wordpress-mobile/issue/1797-error-crash

Prevent crash when WordPressComApi errorMessageForError is called
Fixes an issue where merging an emtpy result set could cause a crash.

Renames a method for consistency.
Reorganizes some code to remove an unnecessary method.
Sets the has more posts flag to false if no resuls are returned.
Fetch existing object and bail if there is an error or the object doesn't exist.
Merge pull request #1800 from wordpress-mobile/release/4.1.1

Merge release/4.1.1 into develop
Merge branch 'develop' of github.com:wordpress-mobile/WordPress-iOS into issues/1778-delete-topics
Add tests for reader cleanup.

Fixes broken tests for accounts and concurrency.
Removes .h file from other test.