Hide the `mapped_memory_page_size` configuration.

I don't think there's any need to put this in front of users.
It's a high-level expert setting and really should only be experimented with by us.
Fix a bug where URIs transaction end-point responses would be wrong.
Merge pull request #3526 from chrisvest/2.2-rest-response-uris

Fix a bug where URIs transaction end-point responses would be wrong.
Merge pull request #3509 from chrisvest/2.2-hide-page-size-config

Hide the `mapped_memory_page_size` configuration.
Fixed issues recently introduced in primitive collections tables
Revert "Fixed issues recently introduced in primitive collections tables"

This reverts commit 269fd6ce13bc6899e4f09b82cfcf7c245fb129f0.
Revert "Merge branch '2.1-maint'"

This reverts commit 2b50d540c795d44f0c80126a913e9a9fccd895ec, reversing
changes made to fae8655a795bbe93214f316ebcf5374ed65a28c8.
Broke out property encoding into separate step
Parallelized property encoding in batch importer

by defering creation of property records until time of writing.
PropertyEncoderStep can have multiple threads encoding properties into
PropertyBlocks, attaching them to each entity.
Moving average for batch importer stats
Dynamically (re)assign processors to slowest importer steps

to optimize steps that are seen to be bottle necks. For this the ability
to have multiple stage execution monitors with individual poll interval,
and a custom task executor with dynamically changable thread count have
been added. Both ExecutorServiceStep and IoQueue uses TaskExecutor.

There's an execution monitor that constantly whatches where processors are
assigned and (re)assigns more or less to those where it sees fit.