Rename storage type inmemory to memory

This is technically a breaking change, but given how long ago this field was implemented as well as the fact that this is the default value if the type is not specified, I doubt anybody's explicitly setting it as inmemory

storage/storage_test.go

@@ -32,13 +32,13 @@ func TestInitialize(t *testing.T) {
 			ExpectedErr: nil,
 		},
 		{
-			Name:        "inmemory-no-file",
-			Cfg:         &Config{Type: TypeInMemory},
+			Name:        "memory-no-file",
+			Cfg:         &Config{Type: TypeMemory},
 			ExpectedErr: nil,
 		},
 		{
-			Name:        "inmemory-with-file",
-			Cfg:         &Config{Type: TypeInMemory, File: t.TempDir() + "/TestInitialize_inmemory-with-file.db"},
+			Name:        "memory-with-file",
+			Cfg:         &Config{Type: TypeMemory, File: t.TempDir() + "/TestInitialize_memory-with-file.db"},
 			ExpectedErr: nil,
 		},
 		{