Metadata improvements - umbrella issue

[Lorak-mmk]

This is an umbrella issue to group all changes regarding the metadata API.

New metadata

• Supporting support UDFs, UDAs & indexes: Schema metadata: support UDFs, UDAs & indexes #1034
• Cluster name: Expose cluster name in metadata #1213

Performance improvements

• Prepare metadata queries: Internal reusable CQL statements should be prepared #417
• Metadata fetching improvements Smarter metadata fetching #1280

Other functionality improvement

• Timeouts: Add timeouts for topology metadata fetch #661
• ControlConnectionPolicy: Implement ControlConnectionPolicy #1279
• StatusChange events should be utilized as hints for keepaliver and refiller #1239