Update mongodb to 2.4.3

Notable changes in 2.4.x:
- Text Search
- New Geospatial Indexes with GeoJSON and Improved Spherical Geometry
- New Hashed Index and Sharding with a Hashed Shard Key
- Role Based Access Control and New Privilege Documents
- Enhanced SSL Support
- Compatibility Change: User Uniqueness Enforced
- --setParameter Option Available on the mongos and mongod Command Line
- Changes to serverStatus Output Including Additional Metrics
- Increased Chunk Migration Write Concern
- BSON Document Validation Enabled by Default for mongod and mongorestore
- Support for Multiple Concurrent Index Builds
- db.killOp() Can Now Kill Foreground Index Builds
- Improved Validation of Index Types
- $setOnInsert - New Update Operator
- Limit Number of Elements in an Array
- JavaScript Engine Changed to V8
- Additional Limitations for Map-Reduce and $where Operations
- Improvements to the Aggregation Framework

See full release notes:

http://docs.mongodb.org/manual/release-notes/2.4/