[REFACTORING] Parsers extracted from Generators::Helpers

Parsers are only responsible for reading data from a corresponding CLI option.

== Addons

* Parsers module
* Parsers::Attribute
* Parsers::Notification
* Parsers::Parameter
[REFACTORING] Decorators added.

Decorators extends parsers by adding method used in templates.

== Addons

* Decorators module.
* Decorators::Base - a base class for decocators.
* Decorators::Attribute
* Decorators::Notification
* Decorators::Parameter
[REFACTORING] Helpers added.

Hexx::Helpers converts CLI option to a list of corresponding decorators.
They also add methods to filter decorators (with some attributes) in templates.

== Addons

* Hexx::Helpers module
* Hexx::Helpers::Base - a base class for helpers.
* Hexx::Helpers::Attributes
* Hexx::Helpers::Notifications
* Hexx::Helpers::Parameters
[REFACTORING] Newly created helpers are used in generators.

== Changes

* Hexx::Helpers (instead of Hexx::Generators::Helpers) are used in BaseModel and Service generators.
* Selection of attributes, parameters and notification removed from generators to corresponding helpers.
* Order of code loading changed in lib/hexx-generators.rb mounting point.

== Deletions

* Hexx::Generators::Helpers
[REFACTORING] Documentation is yard-styled

Documenting comments are styled both in the module classes and its templates.

== Version

Release 0.2.0 (unstable) launched.