Make passenger rubyapp runs as obsapi user.

Passenger's default user is nobody:
 https://www.phusionpassenger.com/library/config/nginx/reference/#passenger_default_user

So that we got Passenger and the RubyApp runs as nobody. However,
according to Debian's SystemGroup usage:
  https://wiki.debian.org/SystemGroups



nogroup (user: nobody): Daemons that need not own any files run as user
nobody and group nogroup. Thus, no files on a system should be owned by
this user or group.

So that we should create a new user call 'obapi' and force passenger app
to run as obs-api instead.

And config files should be readable by that obsapi user but usually not
writable.

Signed-off-by: Andrew Lee (李健秋) <ajqlee@debian.org>
Signed-off-by: Héctor Orón Martínez <hector.oron@collabora.com>

debian/rake-tasks.sh

@@ -26,10 +26,10 @@ case "$1" in
 	chown -R www-data:www-data /usr/share/obs/api/public
 	chown www-data:www-data /etc/obs/api/config/production.sphinx.conf
 	chmod 664 /var/log/obs/*.log
-	chown obsapi:www-data /etc/obs/api/config/database.yml
+	chown obsapi:obsapi /etc/obs/api/config/database.yml
 	chmod 440 /etc/obs/api/config/database.yml
-	chown obsapi:www-data /var/log/obs/backend_access.log
-	chown obsapi:www-data /var/log/obs/production.log
+	chown obsapi:obsapi /var/log/obs/backend_access.log
+	chown obsapi:obsapi /var/log/obs/production.log
 
 	# Generate Gemfile.lock file.
 	cd /usr/share/obs/api