implement session stat command

Implement the session stat command.

Change-Id: I1ff715dd32d963722182db84b475bc9adbfcc7ea
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/src/ipmiblob/blob_interface.hpp b/src/ipmiblob/blob_interface.hpp
index 5d311ee..ece5c34 100644
--- a/src/ipmiblob/blob_interface.hpp
+++ b/src/ipmiblob/blob_interface.hpp
@@ -57,6 +57,14 @@
     virtual StatResponse getStat(const std::string& id) = 0;
 
     /**
+     * Get the stat() on the blob session.
+     *
+     * @param[in] session - the blob session
+     * @return metadata structure
+     */
+    virtual StatResponse getStat(std::uint16_t session) = 0;
+
+    /**
      * Attempt to open the file using the specific data interface flag.
      *
      * @param[in] blob - the blob_id to open.