Updates for expanded storage.

Mount private volumes at /mnt/expand, which is where we have new
SELinux policy waiting for us.  Also ensure that foundational
directories are ready when mounting.

Create local fs_prepare_dir() wrapper that sets SELinux context
based on path, avoiding the need for a later restorecon.

Use UUID as directory name for public volumes.  Wait a few seconds
before issuing first signal when force unmounting.

Bug: 19993667
Change-Id: If22595380faaae321705b06c87d877419620da48
diff --git a/PublicVolume.cpp b/PublicVolume.cpp
index ffcfc67..6192e7a 100644
--- a/PublicVolume.cpp
+++ b/PublicVolume.cpp
@@ -110,7 +110,7 @@
     // Use UUID as stable name, if available
     std::string stableName = getId();
     if (!mFsUuid.empty()) {
-        stableName = "public:" + mFsUuid;
+        stableName = mFsUuid;
     }
 
     mRawPath = StringPrintf("/mnt/media_rw/%s", stableName.c_str());