mysql table DDL: minor, not necessary, but a little more strict

the directory is already hashed into dirhash. So this change is not strictly required.

weed/command/scaffold/filer.toml

@@ -44,7 +44,7 @@ dbFile = "./filer.db"                # sqlite db file
 # CREATE TABLE IF NOT EXISTS filemeta (
 #   dirhash     BIGINT               COMMENT 'first 64 bits of MD5 hash value of directory field',
 #   name        VARCHAR(1000) BINARY COMMENT 'directory or file name',
-#   directory   TEXT                 COMMENT 'full path to parent directory',
+#   directory   TEXT BINARY          COMMENT 'full path to parent directory',
 #   meta        LONGBLOB,
 #   PRIMARY KEY (dirhash, name)
 # ) DEFAULT CHARSET=utf8;
@@ -69,7 +69,7 @@ createTable = """
   CREATE TABLE IF NOT EXISTS ` + "`%s`" + ` (
     dirhash BIGINT,
     name VARCHAR(1000) BINARY,
-    directory TEXT,
+    directory TEXT BINARY,
     meta LONGBLOB,
     PRIMARY KEY (dirhash, name)
   ) DEFAULT CHARSET=utf8;