Log Message:
Update mongodb to 2.6.1.

Notable changes since 2.6.0:
- Fix to install MongoDB service on Windows with the --install option
- Allow direct upgrade from 2.4.x to 2.6.0 via yum
- Fix issues with background index builds on secondaries
- Redact credential information passed as startup options

See full changelog:

http://docs.mongodb.org/manual/release-notes/2.6-changelog/