How to create a Wifi network with Ubuntu 14.04

First of all, install the app-hotspot (before start it, read this entire LucasTipss tutorial):
http://www.edivaldobrito.com.br/como-criar-hotspot-wi-fi-portatil-para-celulares-android-windows-no-ubuntu/

Now, there's a bug with ubuntu 14.04 LTS. To fix it, follow the bellow steps. The solution is a downgrade of the system. (extracted from http://www.webupd8.org/2013/06/how-to-set-up-wireless-hotspot-access.html)

Fot 64-bit:

cd /tmp
wget http://archive.ubuntu.com/ubuntu/pool/universe/w/wpa/hostapd_1.0-3ubuntu2.1_amd64.deb
sudo dpkg -i hostapd*.deb
sudo apt-mark hold hostapd

For 32-bit:

cd /tmp
wget http://archive.ubuntu.com/ubuntu/pool/universe/w/wpa/hostapd_1.0-3ubuntu2.1_i386.deb
sudo dpkg -i hostapd*.deb
sudo apt-mark hold hostapd