Allow customization of settings.LOCAL_ROOT.
Allow customization of settings.LOCAL_ROOT.

This allows a settings_local.py file to override where the local root for
directories such as htdocs should live. Normally, the logic in settings.py
is correct, but in special cases (such as for the docs generation), we need
to be able to specify a custom path.

1tush/reviewboard,Khan/reviewboard,reviewboard/reviewboard,reviewboard/reviewboard,davidt/reviewboard,Khan/reviewboard,Khan/reviewboard,bkochendorfer/reviewboard,KnowNo/reviewboard,chazy/reviewboard,chazy/reviewboard,bkochendorfer/reviewboard,chipx86/reviewboard,reviewboard/reviewboard,atagar/ReviewBoard,1tush/reviewboard,beol/reviewboard,chazy/reviewboard,custode/reviewboard,custode/reviewboard,1tush/reviewboard,chazy/reviewboard,brennie/reviewboard,chazy/reviewboard,Khan/reviewboard,chazy/reviewboard,chazy/reviewboard,beol/reviewboard,brennie/reviewboard,1tush/reviewboard,chipx86/reviewboard,KnowNo/reviewboard,KnowNo/reviewboard,chipx86/reviewboard,sgallagher/reviewboard,sgallagher/reviewboard,Khan/reviewboard,brennie/reviewboard,atagar/ReviewBoard,bkochendorfer/reviewboard,KnowNo/reviewboard,sgallagher/reviewboard,1tush/reviewboard,custode/reviewboard,atagar/ReviewBoard,Khan/reviewboard,atagar/ReviewBoard,1tush/reviewboard,chipx86/reviewboard,1tush/reviewboard,custode/reviewboard,1tush/reviewboard,atagar/ReviewBoard,bkochendorfer/reviewboard,Khan/reviewboard,chazy/reviewboard,davidt/reviewboard,1tush/reviewboard,beol/reviewboard,Khan/reviewboard,chazy/reviewboard,atagar/ReviewBoard,brennie/reviewboard,davidt/reviewboard,beol/reviewboard,reviewboard/reviewboard,atagar/ReviewBoard,davidt/reviewboard,atagar/ReviewBoard,sgallagher/reviewboard,atagar/ReviewBoard,Khan/reviewboard