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

[Thomas Dziedzic]

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.