Implement strict input validation

[dimitriirtimid]

The validation in the Initiative aggregate need to become more strict.

DoD:

• [x] check all command handlers and determine the acceptable ranges for all data attributes
• [x] document the validation here: https://github.com/local-motion/product/blob/master/technical/validations.md
• [x] 'clean' the data where need for instance by trimming strings
• [x] validate all input against their ranges (explicitly check that the range lies within the acceptable ranges as opposed to check for error conditions)
• [x] implement unit tests to verify that the services exhibit the expected behaviour

[dimitriirtimid]

@AnandAili Can you please comment on the status of this issue? Is all input sufficiently validated or are there gaps?

[AnandAili]

This is already done and there are no gaps. Its already in production.

[AnandAili]

I will close this line since the code is already moved to production. For any new validation, new issue will be created.