Update interface implementations to reflect changes to libweave

Pulling current version of libweave and making necessary changes to
weaved implementation of libweave's interfaces

Change-Id: I31d5d00ce1c7d2338257d62ec2dd510608ff71af
diff --git a/buffet/webserv_client.cc b/buffet/webserv_client.cc
index f165849..e79a6a4 100644
--- a/buffet/webserv_client.cc
+++ b/buffet/webserv_client.cc
@@ -19,7 +19,9 @@
 
 namespace {
 
-class RequestImpl : public weave::HttpServer::Request {
+using weave::provider::HttpServer;
+
+class RequestImpl : public HttpServer::Request {
  public:
   explicit RequestImpl(std::unique_ptr<libwebserv::Request> request)
       : request_{std::move(request)} {}
@@ -27,6 +29,7 @@
 
   // HttpServer::Request implementation.
   const std::string& GetPath() const override { return request_->GetPath(); }
+
   std::string GetFirstHeader(const std::string& name) const override {
     return request_->GetFirstHeader(name);
   }