[arch-general] Important changes for mongodb 1.8.2-2

In response to the following bug report https://bugs.archlinux.org/task/24983 I have applied the attached fix to mongodb and as a result there have been some backwards incompatible changes. dbpath has been changed to /var/lib/mongodb logpath has been changed to /var/log/mongodb/mongod.log There have been other minor fixes, please check out the bug report for full details.