Document source code using YUIDoc

[karmacoma]

We should document the lisk-nano source code using: http://yui.github.io/yuidoc/

New code can be documented immediately: http://yui.github.io/yuidoc/syntax/index.html

Existing code we cover here, module by module.

[reyraa]

@karmacoma Please clarify:

• Should all the public method of the services get documented?
• Should we define types for parameters?
  • If yes, Should we check for parameter types in logic?
• Should we add parameter description
• Should we define return types?
  • If yes, Should we restrict functions to a single return type?
• Should we use descriptions?

[reyraa]

As @karmacoma suggested we're going to start with:

• Only for public methods.
• Define types for parameters.
• No descriptions yet.