Fix disparity between config/docs and kup-server

It should be compress_command and decompress_command everywhere.

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
diff --git a/kup-server b/kup-server
index 5c7f40d..8ecf167 100755
--- a/kup-server
+++ b/kup-server
@@ -139,12 +139,12 @@
 		# Do we have a path defined?
 		if (!defined($cfg->param("compressors.${zformat}"))) {
 			# Do we have a section with compress/decompress commands?
-			if (!defined($cfg->param("${zformat}.compress_cmd"))) {
+			if (!defined($cfg->param("${zformat}.compress_command"))) {
 				fatal("Compressor ${zformat} requested, but commands not specified.");
 			}
 			$zformats{$ext} = {
-				'compress'   => $cfg->param("${zformat}.compress_cmd"),
-				'decompress' => $cfg->param("${zformat}.decompress_cmd"),
+				'compress'   => $cfg->param("${zformat}.compress_command"),
+				'decompress' => $cfg->param("${zformat}.decompress_command"),
 			}
         } else {
 			# We have old-style definition, so just add -9 and -cd to it