This worked for me, on a fresh 14.04 vps

sudo apt-get install -y git htop #htop is a proc manager
sudo add-apt-repository ppa:bitcoin/bitcoin
#[ENTER]
sudo apt-get update

sudo apt-get install -y build-essential pkg-config libtool autotools-dev autoconf \
&& sudo apt-get install -y libssl-dev build-essential libtool autotools-dev autoconf automake \
&& sudo apt-get install -y libboost-all-dev \
&& sudo apt-get install -y libdb4.8-dev libdb4.8++-dev \
&& sudo apt-get install -y libqt4-dev libprotobuf-dev protobuf-compiler \
&& sudo apt-get install -y libminiupnpc-dev \
&& sudo apt-get install -y libqrencode-dev \
&& sudo apt-get install -y libgmp3-dev

#after gitclone...in /src: make -f makefile.unix