resolves #31: exception thrown on bad file descriptor

Read or writes to bad file descriptors threw exceptions, just log
this instead. Also make sure that LaminarClients are removed from
the list of clients when a connection is aggressively dropped, and
add test

src/server.h

@@ -48,9 +48,7 @@ private:
     void acceptRpcClient(kj::Own<kj::ConnectionReceiver>&& listener);
     kj::Promise<void> handleFdRead(kj::AsyncInputStream* stream, char* buffer, std::function<void(const char*,size_t)> cb);
 
-    void taskFailed(kj::Exception&& exception) override {
-        kj::throwFatalException(kj::mv(exception));
-    }
+    void taskFailed(kj::Exception&& exception) override;
 
 private:
     struct WebsocketConnection;
@@ -58,9 +56,14 @@ private:
 
     int efd_quit;
     capnp::Capability::Client rpcInterface;
-    HttpImpl* httpInterface;
+    LaminarInterface& laminarInterface;
+    kj::Own<HttpImpl> httpInterface;
     kj::AsyncIoContext ioContext;
     kj::TaskSet tasks;
+
+    // TODO: restructure so this isn't necessary
+    friend class ServerTest;
+    kj::PromiseFulfillerPair<void> httpReady;
 };
 
 #endif // LAMINAR_SERVER_H_