mon/MonClient: use generic Messenger factory

Signed-off-by: Sage Weil <sage@redhat.com>
msg/Message: drop unneeded #include

Signed-off-by: Sage Weil <sage@redhat.com>
msg: make messenger type configurable

Eventaully we may want to override this by passing the type in as an
arg, but let's do that later.

Signed-off-by: Sage Weil <sage@redhat.com>
msg: use localized cct for derr

Signed-off-by: Sage Weil <sage@redhat.com>
librados: use Messenger factory method

Signed-off-by: Sage Weil <sage@redhat.com>
msg: move SimpleMessenger to msg/simple/

Signed-off-by: Sage Weil <sage@redhat.com>
Merge pull request #2652 from ceph/wip-msgr

msgr: fix remaining direct references to "new SimpleMessenger" by replacing with the factory method

Reorganize the src/msg hierarchy to push SimpleMessenger down into a subfolder to make way for organizing new in-tree implementations.

Reviewed-by: Greg Farnum <greg@inktank.com>