Maua client answers Improvements.

Remove hasExplanation parameter from all directives js and html.
Add new property 'hasExplanation' which belongs and it's pre calculate from the practice service to validate if an answer
has explanation or not.
Add new validation to show answer panel analytics just once the 'total answered' it's bigger than 100.
Add new fraction entry logic.

*This explanation validation was being calculated at runtime by a function, which have less performance than have the value already calculate once it gets into the directive.