mds: Add LogEvent::get_type_str()

Signed-off-by: John Spray <john.spray@inktank.com>
common: Add write_stream(ostream) to bufferlist

Enable C++ style file I/O when writing binary output
from bufferlists.

Signed-off-by: John Spray <john.spray@inktank.com>
mds: fix typo 'Sesion'
osdc: Add Sentinel and start_ptr fields to journal

TODO: backwards compat

Signed-off-by: John Spray <john.spray@inktank.com>
HACK: Add get_path method to EMetaBlob

Works for fully local inodes
mds: Create cephfs-journal-tool

Signed-off-by: John Spray <john.spray@inktank.com>