Fix for #3449
Regression test for #3449
Remove obsolete bits of the /ajax endpoint.
Merge branch 'tim/remove-ajax-2879' into next
Merge branch 'next' of github.com:rethinkdb/rethinkdb into next
Destroy kv_location before waiting for the superblock to be returned in erase_small_range. Closes #3455.
Revert "Destroy kv_location before waiting for the superblock to be returned in erase_small_range. Closes #3455."
Committed to 'next' by accident, sorry.

This reverts commit 47762c604a73f260bdec09b4b3af9ce22913ef32.
Destroy kv_location before waiting for the superblock to be returned in erase_small_range. Closes #3455.
Merge branch 'next' of github.com:rethinkdb/rethinkdb into next
Merge branch 'next' into daniel_3455
Fix a bunch of RSIs
Added a warning to find_keyvalue_location_for_write about when the superblock promise is getting pulsed.
Merge branch 'tim/rsi-reql-admin-3233' into next
Merge branch 'next' of github.com:rethinkdb/rethinkdb into next
Fix and regression test for #3444
Merge branch 'daniel_3449' into v1.15.x
Merge branch 'v1.15.x' into next

Conflicts:
	src/btree/leaf_node.cc
Allow outdated reads for table counts
Make use of r.range fix to shorten some queries
Skeletal reconfigure panel implemented