Don't use volume name as snapshot name because volume name may incude space, \ and other special character, which cannot be part of path name in vmware
         after this commit, snapshot name is volumeUuid_timestring.
zero size of template/volume being registered causes infinite loop on SSVM,
the fix is if the size is 0, return success without download
volume size is virtual disk size not physical size, so uploaded volume should use virtual size