fix fstab && better retry logic for docker pull

image/overlay/etc/fstab

@@ -1,4 +1,4 @@
 # /etc/fstab: static file system information
 #
 # <file system>	<mount point>	<type>		<options>		<dump>	<pass>
-/dev/vdb1	/data		ext4	rw,noatime  0   1
+/dev/vdb1	/data		ext4	rw,noatime  0   1

image/overlay/etc/init.d/bubble

@@ -5,10 +5,9 @@ depend() {
 }
 
 start_pre() {
-	 until docker info >/dev/null 2>&1; do
-		  sleep 2
-	 done
-    docker pull git.sfclub.cc/cloud/workspace-image:latest
+    until docker pull git.sfclub.cc/cloud/workspace-image:latest; do
+        sleep 10
+    done
 }
 
 command="/usr/bin/bubble"