Merge packaging changes from Ubuntu 14.04 Trusty and Debian 8 Jessie.
Upgrade nginx-lua to 0.9.7
Upgrade ngx-fancyindex to 0.3.3
Make the regular expression, used in the init script for extracting the path to the PID file, more precise.

Fixes https://code.google.com/p/phusion-passenger/issues/detail?id=1060
Move configuration into config/, library files and internal tools into lib/, developer tools into devtools/
Introduce a setup script which automates installing dependencies, config files, etc.
Merge setup-pbuilder-dist and update-pbuilder-dist into a single program.
Split some more code into bashlib, make every bashlib-using program clean up child processes on exit, and have import_misc_packages hold a lock while doing its work.
When importing misc packages, store git repositories in /var/cache/passenger_apt_automation/misc_packages.

This makes things faster in Vagrant.
import_misc_packages should create a random temporary directory and should clean it up when something goes wrong
Move create_nginx_package.drake to internal/
Rename import_misc_packages to create-dependency-packages and add command line switches to control its behavior
Update documentation
Add trusty to apt distributions list
Update new_release script.

- The directory in which to store APT repositories is now configurable.
- Improve error handling.
- Clean up child processes when killed.
- Give each APT repository update a date-based version number.
Mount the Passenger source directory if available
Update documentation
Make create-dependency-packages work when DEBIAN_ARCHS does not contain i386
Fix bugs
Use Ubuntu 12.04 as Vagrant VM because it better matches the production environment