razor_rpm_open() should take an error parameter, not an atomic

razor_create_root() should take an error pointer

Allow multiple atomic transactions to be used with one root object.
This allows transactions that include barriers to be performed
while holding an exclusive system lock.

Add an error object.
This is intended to dis-entangle the two roles that the atomic
object has evolved into so that atomic need only be used where
atomic actions are actually being undertaken.

Pass script failures up to caller

Fix object management in error paths

Start 0.5.4

Release version 0.5.3

Add transaction barriers
These allow packages to be installed and removed which have scripts
that depend on each other when atomic transactions are involved.
Note that yum supports pre, but not other requires flags. post will
need similar support to the post scripts themselves pulling in the
requires flags from the rpms. Likewise preun and postun will need
similar handling to those scrips since the requires flags will need
to be stored in the razor database.

Add deque_length()