- New WIP for Clean shutdown.
- Changed graceful to clean.  Added also some docs.
- Fixed test_scripts_stop.py.  Changed short option from g to c. Fixed subfunction s/sighup/sigusr1
- Fixed stop_clean.
s/Shutdowns/Shuts down/
- Changed SIGHUP to SIGUSR1.
- Fixed documentation to reflect the new --clean parameter for stop.
fix typo
fix pyflake
Merge branch 'pull554'
relnotes
BuildChooser: refactor (slave,breq) logic into strategy object

 * moved the following logic from Builder to BuildChooser
   - slave choice
   - build choice
   - build merging
 * move the following logic from Builder to BuildRequestDistributor
   - managing the brid reclamation

The slave-choice logic now checks if slaves can grab build locks. Slaves that
can are preferred to slaves that cant.

Also adding a customization point that lets slaves to be chosen based on
particular builds; for example, a patch is coming that will add a ForceScheduler
parameter to force a build onto a particular buildslave.
BuildChooser: Fix up comments
BuildChooser: minor enhancements
BuildChooser: address review comments; pyflakes too
Fix pyflakes issue
BuildChooser: address review issues; beef up comments