cephadm: start decorators.py in cephadmlib

cephadm: start decorators.py in cephadmlib

Originally, wanted to move all the decorators into
their own files. Unfortunately, that isn't possible
at this time as most of them depend on things that
are still within cephadm.py This includes

list_daemons
_rm_cluster
is_fsid
termcolor
ContainerInfo
Ceph

and I'm sure I'm missing some others. We'll have to
revisit this again later when more of these things
have moved, or they can be slowly moved as their
dependencies are.

Signed-off-by: Adam King <adking@redhat.com>