Updated config.jelly to use public accessors

config.jelly was trying to access the private boolean fields of
BazaarSCM directly, which resulted in in the checkboxes not being
populated when returning to the project configuration page.  Updated to
use the public accessor functions for checkout and cleantree with fixes
the issue.
Merge pull request #9 from RyanHerbert/master

config.jelly was trying to access the private boolean fields of
BazaarSCM directly. Use public methods instead, harmony and light results.