vold: Add encrypted ASEC support via devmapper

- Supports up to 4096 containers
- Keys are now implemented - specifying a key of 'none' means no encryption.
  Otherwise, the key must be a string of 32 characters

Signed-off-by: San Mehat <san@google.com>
diff --git a/Loop.h b/Loop.h
index 1ade4f9..da91dc2 100644
--- a/Loop.h
+++ b/Loop.h
@@ -22,7 +22,7 @@
 
 class Loop {
 public:
-    static const int LOOP_MAX = 255;
+    static const int LOOP_MAX = 4096;
 public:
     static int lookupActive(const char *loopFile, char *buffer, size_t len);
     static int create(const char *loopFile, char *loopDeviceBuffer, size_t len);