Improve stylesheet structure
Allow feats to be stackable

Setting the stackable boolean to true, will allow the character to take
the same feat multiple times.
Attaches skills to characters

This patch allows character classes to have skills as class skills and
cross class skills. Characters with a given level can only choose from
the skills that’s available to his character class.
Allow Skill.available_for to take character or character class

`Skill.available_for` now takes either a Character instance or a
CharacterClass instance. In the case of the Character instance,
available skills for the last added level’s CharacterClass will be
returned. In the case of a CharacterClass instance, all available
skills for the Character class instance will be returned.
Don't log assets

This is annoying to watch in the logs. So for development, asset
logging has been disabled.
Allows attaching skills to characters

When a hash of skill ids and ranks is posted, the skills which are
available will be added to the character. If the skill is already
there, the rank willl be set to the supplied rank.

This also implements Character#last_level, which returns the last added
level to the character.
Test application controller exception rescuing.
Test home controller
Refactor levelup flow

This completely remodels, -structures and -factors the levelup
proceedure. It’s now faster and more reliable.