Add grpc client tls certificate

[vctt94]

This PR depends on https://github.com/jrick/dcrwallet/tree/clientauth.

It adds tls client certificate into grpc client.

[matheusd]

FYI, here's the minimal diff to pass on the required client auth and cert from decrediton to dcrlnd. This requires decred/dcrlnd#110 and it also requires bringing in the most recent walletunlocker.proto and regenerating the dcrlnd gRPC bindings, however doing that will make this conflict with #2641 (so you won't be able to test it until 2641 is merged or by manually modifying the local rpc.proto file)

diff --git a/app/actions/LNActions.js b/app/actions/LNActions.js
index ee0ad36b..73e072f0 100644
--- a/app/actions/LNActions.js
+++ b/app/actions/LNActions.js
@@ -85,6 +85,7 @@ export const startDcrlnd = (
   }
 
   const rpcCreds = ipcRenderer.sendSync("get-dcrd-rpc-credentials");
+  const walletClientKeyCert = wallet.getDcrwalletGrpcKeyCert();
 
   let dcrlndCreds;
   let wuClient;
@@ -140,7 +141,7 @@ export const startDcrlnd = (
       stage: LNWALLET_STARTUPSTAGE_UNLOCK,
       type: LNWALLET_STARTUP_CHANGEDSTAGE
     });
-    await ln.unlockWallet(wuClient, passphrase);
+    await ln.unlockWallet(wuClient, passphrase, walletClientKeyCert);
   } catch (error) {
     // An unimplemented error here probably means dcrlnd was already running,
     // so just continue with the connection attempt.
diff --git a/app/wallet/ln/index.js b/app/wallet/ln/index.js
index 1311660b..180d495c 100644
--- a/app/wallet/ln/index.js
+++ b/app/wallet/ln/index.js
@@ -267,10 +267,11 @@ export const sendCoins = (client, address, amount) => {
   );
 };
 
-export const unlockWallet = (wuClient, passphrase) => {
+export const unlockWallet = (wuClient, passphrase, dcrwClientKeyCert) => {
   const request = new pb.UnlockWalletRequest();
   const bytesPassphrase = new Uint8Array(Buffer.from(passphrase));
   request.setWalletPassword(bytesPassphrase);
+  request.setDcrwClientKeyCert(dcrwClientKeyCert);
 
   return new Promise((resolve, reject) =>
     wuClient.unlockWallet(request, (err, resp) =>

[alexlyp]

tACK