Add character progression

[afonsolage]

Add character progression (gain exp/fame/expertise) whenever one of the following actions is done:

• Mobs is killed - In this case the player gets exp with all current equipped items;
• Gather - Get exp whenever the player collects somethings with isn't a Drop Bag (like resources or gather mobs);

This system should be expanded when new features get added to the game, like crafting, building, commerce, PvP and so on.