Tomcat7 on Ubuntu 14.04 with Oracle Java running on port 80

Start with installing Oracle Java

sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java8-installer

Now install tomcat7

sudo apt-get install tomcat7

To run on ports below 1024, authbind needs to be enabled

sudo nano /etc/default/tomcat7

change #AUTHBIND=no to AUTHBIND=yes

sudo touch /etc/authbind/byport/80
sudo chmod 500 /etc/authbind/byport/80
sudo chown tomcat7 /etc/authbind/byport/80

set JAVA_HOME

sudo nano /etc/default/tomcat7

Add JAVA_HOME=/usr/lib/jvm/java-8-oracle

You should now be able to start tomcat7