Pass a "nested.property" to Validator.validateProperty

[fkleuver]

I'm submitting a feature request

Current behavior:
Given a Rule with a nested property accessor (like "some.nested.property"), the accessor is treated as a single property rather than nested properties, e.g. obj["some.nested.property"]

Expected/desired behavior:
The property to be accessed like so: obj.some.nested.property

This is my proposed solution (line 108 for the function call; the function itself is at the bottom): https://github.com/fkleuver/validation/blob/master/src/implementation/standard-validator.ts

What is the motivation / use case for changing the behavior?
When dynamically generating validation rules from arbitrary JSON, it's not always possible/practical to stick to direct property accessors. It appears to be relatively simple to implement, but correct me if I'm overseeing something!

[jdanyow]

#283