add dynamic library interface to enable testing

Add interface defining the methods for dynamic linking to enable
testing.

Change-Id: If4d090d3cedc019b426435a1f651191803bfc1a9
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/main.cpp b/main.cpp
index 5fdb53d..ee236d9 100644
--- a/main.cpp
+++ b/main.cpp
@@ -78,7 +78,7 @@
     /* Install handlers. */
     try
     {
-        loadLibraries(expectedHandlerPath);
+        loadLibraries(getBlobManager(), expectedHandlerPath);
     }
     catch (const std::exception& e)
     {