Improvements

[sdelamo]

This PR :

• Renames migration to 103. 102 already exists.
• Remove public access modifiers from the test.
• uses @ExecuteOn(TaskExecutors.BLOCKING) instead of IO
• remove unnecessary parenthesis from annotations. E.g. @Post not @Post()
• don't use Project Reactor code in the controller which is unnecessary.
• Use URIBuilder to create URI.
• Adds findByName method to repository.