Use new installer feature from packager.io

Postinstall for openproject is now in its own addon at https://github.com/pkgr/addon-openproject.

Conflicts:

	.pkgr.yml
Add addon-legacy-installer
Removal of builpack entry
Add ruby 2.3.1 to setup
add rake tasks for mysql db backups/restores
postgresql db backups
add specs for backup task
whitespace fixes and other minor things
only sanitize_filename the actual filename
do not use the PGPASSFILE if no password is provided
db backup filename depends on db adapter
pg_dump needs the database name as the last param
Add /backup to .gitignore
hound config that matches `dev`
Merge pull request #2083 from opf/feature/hound_for_release

hound config that matches `dev`
fix timeline float behavior

When we clear both, the float of the project menu is also factored in.
Merge pull request #2088 from opf/backport/fix_timeline_float
Merge pull request #2082 from opf/feature/backup_task_3-0

rake task to backup and restore the database
Merge pull request #2076 from opf/feature/packager-new-installer-stable

Use new packager installer
dead code removal