[REFACTORING] ActiveRecord::ErrorsCollector -> ActiveRecord::Collector

== Changes (API implementation)

* Hexx::ActiveRecord::ErrorsCollector -> Hexx::ActiveRecord::Collector
* Hexx::ActiveRecord::Collector.collect -> Hexx::ActiveRecord::Collector.add
[DEPENDENCY] updated to hexx v6.0.2

== Changes (backward-incompatible)

* 'hexx' v5.0 -> v6.0.2
* Hexx::Models -> Hexx::Coercible
  Renamed to follow naming convention: the module is named by the property,
  that it adds to extended class.
* Hexx::ActiveRecord::Coercer -> Hexx::ActiveRecord::Coersion
  Renamed to follow Hexx naming convention: the constructror class is named
  by the attribute it constructs in the target class/module.