Cass types v2

[Lorak-mmk]

This is a continuation of https://github.com/hackathon-rust-cpp/cpp-rust-driver/pull/18 Changes from original PR:

• Derive PartialOrd and PartialEq for generated enums
• Reorder functions in cass_types to the same order as in spreadsheet.
• Reimplement cass_data_type_new - it's behaviour should depend on argument, as in cppdriver
• Add strlen helper function
• Implement missing variants of CassDataType
• Implement missing function of CassDataType - apart from is_frozen (I can't see a scenario where it returns true)
• CassDataType is now Arc, otherwise it's impossible to be semantically compatible with cppdriver.
• Overhaul of CassUserType (use macros to generate binding functions, binders for more values)

[Lorak-mmk]

Closing, refactored changes in https://github.com/hackathon-rust-cpp/cpp-rust-driver/pull/59 and https://github.com/hackathon-rust-cpp/cpp-rust-driver/pull/60