Obtain absoute path of configuration file, expose it in INFO.
CONFIG REWRITE: Initial support code and design.
CONFIG REWRITE: support for save and syslog-facility.
CONFIG REWRITE: support for dir and slaveof.
CONFIG REWRITE: support for client-output-buffer-limit.
CONFIG REWRITE: strip multiple empty lines.
CONFIG REWRITE: remove orphaned lines.
CONFIG REWRITE: actually rewrite the config file, atomically.
CONFIG REWRITE: Use sane perms when creating redis.conf from scratch.
Merge remote branch 'upstream/config-rewrite' into unstable