package securedrop app and monitor servers as debian packages

Changes installation method into debian packages
To build packages:
* run `securedrop/install_files/build_deb_packages.sh` 

If you are using vagrant you can use the included vagrant-app-preinstall.sh and vagrant-monitor-preinstall.sh scripts to preseed most questions and add the tor repo.

Otherwise:
On App server you will need; an OS user account, the application gpg key, the add-repos.sh script, and the app, source and document deb packages.
```
./add-repos.sh
dpkg -i app-0.2.1-dev.deb
apt-get install -f
dpkg -i app-0.2.1-dev.deb
```

On the Monitor server you will need an OS user account and the monitor deb package.
```
./add-repos.sh
dpkg -i monitor-0.2.1-dev.deb
apt-get install -f
dpkg -i monitor-0.2.1-dev.deb
```
* Need to change license to reflect openssl code exemption for OSSEC and credit alien vault's debian ossec package
* Need to imporve removes/purges so the system is in same state as before install
* Need to break up app package into three packages app-chroot app-ossec app-hardening. Currently the app postinst is too long and complex
* Need to update appamror profiles
* Need to rename deb packages to debian standard
* Production install will not work till the packages are in a public repo

lots of help from @ageis