Added README

README.md

+        usage: totalbackup [options]
+
+        optional arguments:
+          -h, --help            show this help message and exit
+          --primary [CONFIG [CONFIG ...]]
+                                backup as specified in CONFIG
+          --secondary SOCKET MOUNT PATH
+                                backup from SOCKET to MOUNT/PATH2
+          --xattr               let md5toc store MD5 in extended attribute
+          --max-age SECONDS     maximum SECONDS since last MD5 calculation
+          --user USER           ssh USER for secondary (-l)
+          --identity IDENTITY   ssh IDENTITY for secondary (-i)
+          --debug               debug actions