Add decorator to register exceptions.
Improve unauthorized error messages.
add pragmas for temp_store=mem and synchronous=off

controlled by environmental variables
Merge remote-tracking branch 'refs/remotes/kali/feature/sqlite_optimization_pragmas' into develop
Merge remote-tracking branch 'refs/remotes/drebs/improve-unauthorized-errors' into develop
Always return unicode, even on UnicodeError.
Merge remote-tracking branch 'refs/remotes/ivan/bug/always-return-unicode' into develop
Add script to find max upload size (#5011).
Merge remote-tracking branch 'refs/remotes/drebs/add-script-to-find-max-upload-size' into develop
Add sphinx doc.
Merge remote-tracking branch 'drebs-github/add-sphinx-doc' into develop
Remove global client rw lock

leap.mail is handling locks in a finer-grained way now,
so we do not need to block everything so much
add locks for create_doc and update_indexes. Closes: #5139

This solves a InterfaceError (sqlite error code 21)
we were having with massive concurrent creation/puts.
Set Write-Ahead Logging

with autocommit set to 50 pages, a value that will permit fast reads.
also set synchronous mode to normal on regular operation.
changes file
Merge remote-tracking branch 'refs/remotes/kali/feature/perf-tweaks' into develop
backward-compatibility for socket.create_connection in 2.6
Closes: #5208
Merge remote-tracking branch 'refs/remotes/kali/bug/soledad-client-socket-2.6' into develop
Improve local db script.
Merge remote-tracking branch 'refs/remotes/drebs/feature/improve-local-db-script' into develop