feat(http): support SSL certificate authentication

You can now pass an agent object on a request with the properties "key" and "cert".
These will be passed to superagent. This feature is primarily useful on
Node.js servers.

http/README.md

@@ -174,6 +174,8 @@ on the response Observable.
 `path`, and `filename` of a resource to upload.
 - `withCredentials` *(Boolean)*: enables the ability to send cookies from the
 origin.
+- `agent` *(Object)*: an object specifying `cert` and `key` for SSL certificate
+authentication.
 - `redirects` *(Number)*: number of redirects to follow.
 - `lazy` *(Boolean)*: whether or not this request runs lazily, which means
 the request happens if and only if its corresponding response stream from the

http/src/http-driver.ts

@@ -45,6 +45,10 @@ export function optionsToSuperagent(rawReqOptions: RequestOptions) {
   if (reqOptions.withCredentials) {
     request = request.withCredentials();
   }
+  if (reqOptions.agent) {
+    request = request.key(reqOptions.agent.key);
+    request = request.cert(reqOptions.agent.cert);
+  }
   if (typeof reqOptions.user === 'string' && typeof reqOptions.password === 'string') {
     request = request.auth(reqOptions.user, reqOptions.password);
   }

http/src/interfaces.ts

@@ -4,6 +4,11 @@ export interface Attachment {
   filename?: string;
 }
 
+export interface AgentOptions {
+  key: string;
+  cert: string;
+}
+
 export interface RequestOptions {
   url: string;
   method?: string;
@@ -17,6 +22,7 @@ export interface RequestOptions {
   field?: Object;
   progress?: boolean;
   attach?: Array<Attachment>;
+  agent?: AgentOptions;
   withCredentials?: boolean;
   redirects?: number;
   category?: string;