rgw: date string parsing also parses seconds fraction

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>
Makefile.am: some more makefile rules fixes

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>
rgw: cls_log_entry has id field

The id field can be used as the marker for log list / trim
operations.

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>
rgw: update log APIs to use markers

a few APIs were missing markers, fixed that.

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>
rgw: relax marker requirements for log apis

Don't require start-time, start-marker.

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>
rgw: end-marker serves as last value, not as upperbound

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>