source/journalist documentation

separates source and journalist user manual, updated for 0.3. updated readme.md. also updated full_install.md up the point of running the ansible-playbook. still need to merge that doc with install.md but wanted to discuss before doing so
This is only if you're using nano for your editor. Replace with something like "After changing the IP address, save the changes to the inventory file and quit the editor." You could also add ("if you're using Nano, hit 'control+O'...") but honesty people who don't know how to use text editors should not be administering a SecureDrop installation.