Renamed mongod to mongodb value for Debian

This affects #10, before I couldn't install mongodb at all, when ppa set
to false.
Merge pull request #11 from holms/master

Renamed mongod to mongodb value for Debian
Fixed conf file name

mongod.conf file would get created, but the service started with mongodb.conf.
Merge pull request #13 from eglute/master

Fixed conf file name
Typo fix
Merge pull request #15 from amr/patch-1

Typo fix