Add support for per-experiment booking duration

[timdrysdale]

Each experiment may have quite different use-cases, so setting global booking duration options is less flexible than ideal. This can be configured in a number of ways

• add configuration to the booking server
• add configuration to a separate location (perhaps separating the concern of max booking duration possible at booking system, from max user-facing booking duration options)

This will need looking at in light of any upgrades to booking procedures that may take place in the v1 release project

[timdrysdale]

Done by moving to new book API