Return explicit error when a volume is unknown.
Fixed mistake in rozo man page.
Added possibility to restart a storage node with rebuild processes
[rozo](issue: #47).
Add possibility to read export hostname (-E| --export option) directly
from the ROZO_EXPORT_HOSTNAME environment variable [rozo].
Added possibility to use either one or several hostnames for the exportd
[rozo].
Merge branch 'hotfix/1.5.2' of https://github.com/rozofs/rozofs into hotfix/1.5.2
Fixed compilation warning.