SERVER-14352 (rocksdb) fixed getSpaceUsedBytes()

Signed-off-by: Benety Goh <benety@mongodb.com>
SERVER-13635 release record store before restarting engine in Restart1 test case
SERVER-13635 No system.indexes in jstests/replsets
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.
SERVER-13635: fix compile on record store test for mmap
SERVER-13635: turn off padding for mmapv1 test
Merge branch 'master' of https://github.com/mongodb/mongo into kv_dictionary

Conflicts:
	src/mongo/db/storage/kv/kv_engine_test_harness.cpp
Remove tailable logic parameter from kv/kv_record_store.{cpp,h}
Fix record store iterator positioning and state saving mechanism.
Fix dataFor to pass an owned RecordData
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