Try running these commands again:
wget http://launchpadlibrarian.net/118496707/libminiupnpc8_1.6-3ubuntu2_armhf.deb
sudo dpkg -i libminiupnpc8_1.6-3ubuntu2_armhf.deb
sudo apt-get install software-properties-common -y
sudo apt-get install -f
Then run this command:
sudo apt-get install gridcoinresearch-qt -y -f
Let me know if that works!
RE: How to Install a Gridcoin Wallet on a Raspberry Pi