SERVER-15273 Only quantize to exact bucket sizes

Prep for new freelist implementation.
SERVER-14081 Add more deletedList buckets to cover more sizes

This is done in a backward compatible way without orphaning any old data.
Downgrading after this patch *will* orphan large (>=4MB) deleted records, but
they will be usable again after upgrading. Additionally, the compact command
should not be run on a downgraded server until SERVER-15319 is resolved.
SERVER-15319 Bump file versions for 2.8-style freelist
SERVER-15373 Add noPadding flag to reduce disk usage for insert-only workloads
SERVER-15319 Multiversion test for freelist upgrade-downgrade
SERVER-13635 lift tailable out of StorageEngine API and handle in query layer.