Reorganisation and clean-up of placeless auth and security.
Patches applied:

 * steve.alexander@canonical.com/launchpad--devel--0--patch-150
   refuel

 * steve.alexander@canonical.com/launchpad--devel--0--patch-151
   tidied up the placeless auth code.

 * steve.alexander@canonical.com/launchpad--devel--0--patch-152
   moved authorization module containing the security policy code into webapp.

 * steve.alexander@canonical.com/launchpad--devel--0--patch-153
   removed decoy sourceutility.py

 * steve.alexander@canonical.com/launchpad--devel--0--patch-154
   reorg of placeless auth code in preparation for it to me moved to c.l.webapp.  Removal of most explicit use of SSHADigestEncryptor to use an IPasswordEncryptor utility instead.

 * steve.alexander@canonical.com/launchpad--devel--0--patch-155
   fix bad import in authorization.py.  improve comments

 * steve.alexander@canonical.com/launchpad--devel--0--patch-156
   refuel

 * steve.alexander@canonical.com/launchpad--devel--0--patch-157
   removed test for previously removed decoy module

 * steve.alexander@canonical.com/launchpad--devel--0--patch-158
   refuel

 * steve.alexander@canonical.com/launchpad--devel--0--patch-159
   fixed typo