Invalid GlusterFS share format error

When we provide invalid GlusterFS share format in GlusterFS shares
configuration file (glusterfs_shares_config), it will log a
Warning message in the volume log file, which not easily discover
able while debugging.

So, this patch changing Invalid GlusterFS share Warning message to
Error message.

Change-Id: I24d47dafc56490d40bd81256135f4b13fce5614a
Merge "Invalid GlusterFS share format error"