fixes some coding style issues

test/integration/provider.cc

@@ -12,7 +12,7 @@ namespace webfuse_test
 class Provider::Private
 {
 public:
-    Private(char const * url)
+    explicit Private(char const * url)
     : is_shutdown_requested(false)
     {
         config = wfp_client_config_create();

test/integration/provider.hpp

@@ -7,7 +7,7 @@ namespace webfuse_test
 class Provider
 {
 public:
-    Provider(char const * url);
+    explicit Provider(char const * url);
     ~Provider();
 private:
     class Private;

test/integration/test_integration.cc

@@ -28,6 +28,8 @@ namespace
     {
         public:
             IntegrationTest()
+            : server(nullptr)
+            , provider(nullptr)
             {
                 json_object_seed(0);
                 wf_lwslog_disable();