Add support for updating local cache through patches

- refactor some code:
   - code handling the file cache is now in fuse/filecache.c
   - base36 and base16 encoding and decoding moved to utils/hash.c
 - mfshell: add "updates" command calling device/get_updates
 - add container class to store patch information as mfapi/patch.c
 - apicalls: store more info retrieved by file/get_info
 - apicalls: add device/get_updates
 - apicalls: add device/get_patch

mfshell/mfshell.c

@@ -56,6 +56,8 @@ struct mfcmd    commands[] = {
     {"status", "", "device status", mfshell_cmd_status},
     {"changes", "<revision>", "device changes (default: 0)",
      mfshell_cmd_changes},
+    {"updates", "[quickkey] [revision]", "list available updates for a file",
+     mfshell_cmd_updates},
     {NULL, NULL, NULL, NULL}
 };