parking some wip code.
Removed old 012->013 upgrade migrations.
wip refactor.
Merge branch 'master' into 20834_tank_commands_api
fixed a cyclic reference
API Adjustments. Added validate command.
converted configurations command
added clear_cache and cache_apps
restricts to single log handler by default.
Added api support for app_info
added param validation. added core localize api support.
Added core upgrade.
added install_app and install_engine
update command
setup project
adjusted default log level.
added tk.list_commands() method. Fixed missing @property
added API support for clone configuration
in lieu of migrations, added an error informing any clients still on
early 0.13 to contact us.
Code review feedback: Better doc strings for public interface