Update to version 0.8.8. (Ok joerg@)  Some changes:

* The ``MasterShellCommand`` step now correctly handles environment
  variables passed as list.
* The master now poll the database for pending tasks when running buildbot
  in multi-master mode.
* Rewritten algorithm to match build requests to slaves
* Slaves can be paused through the web status

Many other fixes and minor changes.

(riz)