profile: refactor profile fields display process

Also displays every field that is not defined in any category in the
last category called "General". Fields are now easily moved between
categories and categories a easily created.

Fields html generation centered in only one method and the field name
and value are customizable through methods.

Fix #14
Merge branch 'profile-fields-stable' into 'stable'

Refactor profile fields

Some fields were not being displayed on profile tab.
To fix this, I refactored the fields construction logic into a more generic and declarative one.
I also added a new category called "General" that will group fields that are not alraedy grouped in any other cateogory.

See merge request !336