change guild upgrade base damage static to percentage

[Brouwer]

(12-29-2015, 10:13 AM)vosavo Wrote: You can simply :
- make the base damage upgrade in the guild's system both damage and % boost [making it eventually become % is meh]
ex/ level 2:  + 80 damage & + 2% base damage.

The % boost should be smaller if it was multiplicative. I would give it 0.5% per level.