Log when creating database from scratch
Merge pull request #1379 from djmitche/log-empty-db

Log when creating database from scratch
Adapt docker tests (follow-up of PR-1366)
Merge pull request #1381 from benallard/docker_tests

Adapt docker tests (follow-up of PR-1366)
Enforce Property name and source as unicode or ascii string
Merge benallard/buildbot:properties_unicode (PR #1382)
Introduce the build_properties table
Fix ordering of buildslave and builder reconfig
fix pyflakes
Fix typo in parameter name.
Merge benallard/buildbot:patch-3 (PR #1383)
Add buildproperties db API
Merge pull request #1384 from benallard/build_properties_db

Build properties db
Don't allow non-JSON-able properties any more
Make pep8 happy
Merge pull request #1385 from benallard/no-json-no-property

Don't allow non-JSON-able properties any more
List all changes related to a build.
 - to do this, the column 'parent_changeid' was added to the table changes
 - traverse the change graph backward from the current build until it found a change for which a successful build on the same builder had been performed.
 - use repository/branch/codebase of sourcestamps as a criteria to found the previous build
 - getParentChangeId to getParentChangeIds
 - parent_changeid to parent_changeids
 - update documentation
Fix sa2ajj's comments
Fix BuildProperty row name (set singular)
indentation