created securedrop-app deb package that packages the app code, apparmor profiles and compiles and pakcages the python modules for deployment.
modified the build_deb to just create the securedrop-app deb
combined source-requirements and document-requirements.txt since they are both running on same apache instance now.
Merge pull request #1 from dolanjs/app-code-deb-for-ansible

securedrop-app deb package for ansible deployment