Release v0.5.0

• Lowercase ObjectId string

Release v0.4.4

• Add getters for Bson

Release v0.4.3

• Fixed bug while converting floating point Value to Bson

Release v0.4.2

• Removed rustc-serialize
• Add missing docs

Release v0.4.1

• Remove rustc-serialize
• Preserve order in JSON
• Uses serde-json instead
• Uses data-encoding for serializing