Drop infinity-agent

Overall it is a bad practice to 'fix' internal modules within the other module.

I think graceful-fs (https://github.com/isaacs/node-graceful-fs#global-patching) is good example, how to do this:

```js
var http = require('http');
var https = requrie('https');

var infinityAgent = require('infinity-agent');
infinityAgent.patch(http);
infinityAgent.patch(https);
```

This will enable global agent tuning in edge cases.

Closes #73 and closes #60

index.js

@@ -6,7 +6,6 @@ var util = require('util');
 var zlib = require('zlib');
 var querystring = require('querystring');
 var objectAssign = require('object-assign');
-var infinityAgent = require('infinity-agent');
 var duplexify = require('duplexify');
 var isStream = require('is-stream');
 var readAllStream = require('read-all-stream');
@@ -35,9 +34,7 @@ function got(url, opts, cb) {
 	}
 
 	opts = objectAssign(
-		{
+		{protocol: 'http:'},
-			protocol: 'http:'
-		},
 		typeof url === 'string' ? urlLib.parse(prependHttp(url)) : url,
 		opts
 	);
@@ -110,29 +107,6 @@ function got(url, opts, cb) {
 		var fn = opts.protocol === 'https:' ? https : http;
 		var url = urlLib.format(opts);
 
-		if (opts.agent === undefined) {
-			opts.agent = infinityAgent[fn === https ? 'https' : 'http'].globalAgent;
-
-			if (process.version.indexOf('v0.10') === 0 && fn === https && (
-				typeof opts.ca !== 'undefined' ||
-				typeof opts.cert !== 'undefined' ||
-				typeof opts.ciphers !== 'undefined' ||
-				typeof opts.key !== 'undefined' ||
-				typeof opts.passphrase !== 'undefined' ||
-				typeof opts.pfx !== 'undefined' ||
-				typeof opts.rejectUnauthorized !== 'undefined')) {
-				opts.agent = new infinityAgent.https.Agent({
-					ca: opts.ca,
-					cert: opts.cert,
-					ciphers: opts.ciphers,
-					key: opts.key,
-					passphrase: opts.passphrase,
-					pfx: opts.pfx,
-					rejectUnauthorized: opts.rejectUnauthorized
-				});
-			}
-		}
-
 		var req = fn.request(opts, function (response) {
 			var statusCode = response.statusCode;
 			var res = response;

readme.md

@@ -102,14 +102,6 @@ Type: `number`
 
 Milliseconds after which the request will be aborted and an error event with `ETIMEDOUT` code will be emitted.
 
-###### agent
-
-[http.Agent](http://nodejs.org/api/http.html#http_class_http_agent) instance.
-
-If `undefined` - [`infinity-agent`](https://github.com/floatdrop/infinity-agent) will be used to backport Agent class from Node.js core.
-
-To use default [globalAgent](http://nodejs.org/api/http.html#http_http_globalagent) just pass `null`.
-
 ##### callback(error, data, response)
 
 ###### error
@@ -185,6 +177,18 @@ got('todomvc.com', {
 ```
 
 
+## Node 0.10
+
+It is a known issue with Node [http.Agent](https://nodejs.org/docs/v0.10.39/api/http.html#http_class_http_agent) and `agent.maxSockets`, which is set to `5`. This can cause low performance of application and (in rare cases) deadlocks. To avoid this you can set it manually:
+
+```js
+require('http').globalAgent.maxSockets = Infinity;
+require('https').globalAgent.maxSockets = Infinity;
+```
+
+This should only ever be done at the top-level application layer.
+
+
 ## Related
 
 - [gh-got](https://github.com/sindresorhus/gh-got) - Convenience wrapper for interacting with the GitHub API