rename write,read to writeMeta,readMeta

The blobs::DataInterface specifies two methods, write and read which are
meant to be implemented to write or read configuration for the data
interface implementation.

Change-Id: I831a8611596fca50570a4156cbdcfa5c810c0315
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/firmware_handler.cpp b/firmware_handler.cpp
index f2740c7..3c47e51 100644
--- a/firmware_handler.cpp
+++ b/firmware_handler.cpp
@@ -227,7 +227,7 @@
     meta->metadata.clear();
     if (item->second->dataHandler)
     {
-        auto bytes = item->second->dataHandler->read();
+        auto bytes = item->second->dataHandler->readMeta();
         meta->metadata.insert(meta->metadata.begin(), bytes.begin(),
                               bytes.end());
     }
@@ -484,7 +484,7 @@
         return false;
     }
 
-    return item->second->dataHandler->write(data);
+    return item->second->dataHandler->writeMeta(data);
 }
 
 /*