Follow up to #1070:

- Adding information in README for socketPath when used with a proxy
- Adding an HTTP test for socketPath option

test/unit/adapters/http.js

@@ -1,5 +1,6 @@
 var axios = require('../../../index');
 var http = require('http');
+var net = require('net');
 var url = require('url');
 var zlib = require('zlib');
 var fs = require('fs');
@@ -228,6 +229,24 @@ module.exports = {
     });
   },
 
+  testSocket: function (test) {
+    server = net.createServer(function (socket) {
+      socket.on('data', function() {
+        socket.end('HTTP/1.1 200 OK\r\n\r\n');
+      });
+    }).listen('./test.sock', function() {
+      axios({
+        socketPath: './test.sock',
+        url: '/'
+      })
+      .then(function(resp) {
+        test.equal(resp.status, 200);
+        test.equal(resp.statusText, 'OK');
+        test.done();
+      });
+    });
+  },
+
   testStream: function(test) {
     server = http.createServer(function (req, res) {
       req.pipe(res);