Added setTopic implementation

lib/Client/Client.js

@@ -460,6 +460,24 @@ var Client = (function (_EventEmitter) {
 		});
 	};
 
+	// def setTopic
+
+	Client.prototype.setTopic = function setTopic(channel, topic) {
+		var callback = arguments.length <= 2 || arguments[2] === undefined ? function (err) {} : arguments[2];
+
+		var self = this;
+		return new Promise(function (resolve, reject) {
+
+			self.internal.setTopic(channel, topic).then(function () {
+				callback();
+				resolve();
+			})["catch"](function (e) {
+				callback(e);
+				reject(e);
+			});
+		});
+	};
+
 	_createClass(Client, [{
 		key: "users",
 		get: function get() {

lib/Client/InternalClient.js

@@ -729,6 +729,34 @@ var InternalClient = (function () {
 		});
 	};
 
+	//def setTopic
+
+	InternalClient.prototype.setTopic = function setTopic(chann) {
+		var topic = arguments.length <= 1 || arguments[1] === undefined ? "" : arguments[1];
+
+		var self = this;
+		return new Promise(function (resolve, reject) {
+
+			self.resolver.resolveChannel(chann).then(next)["catch"](reject);
+
+			function next(channel) {
+
+				request.patch(Endpoints.CHANNEL(channel.id)).set("authorization", self.token).send({
+					name: channel.name,
+					position: 0,
+					topic: topic
+				}).end(function (err, res) {
+					if (err) {
+						reject(err);
+					} else {
+						channel.topic = res.body.topic;
+						resolve();
+					}
+				});
+			}
+		});
+	};
+
 	InternalClient.prototype.sendWS = function sendWS(object) {
 		if (this.websocket) this.websocket.send(JSON.stringify(object));
 	};

src/Client/Client.js

@@ -441,6 +441,24 @@ class Client extends EventEmitter {
 			
 		});
 	}
+	
+	// def setTopic
+	setTopic(channel, topic, callback=function(err){}){
+		var self = this;
+		return new Promise((resolve, reject) => {
+			
+			self.internal.setTopic(channel, topic)
+				.then(() => {
+					callback();
+					resolve();
+				})
+				.catch(e => {
+					callback(e);
+					reject(e);
+				});
+			
+		})
+	}
 }
 
 module.exports = Client;

src/Client/InternalClient.js

@@ -776,6 +776,37 @@ class InternalClient {
 				}
 		});
 	}
+	
+	//def setTopic
+	setTopic(chann, topic=""){
+		var self = this;
+		return new Promise((resolve, reject) => {
+			
+			self.resolver.resolveChannel(chann).then(next).catch(reject);
+			
+			function next(channel){
+				
+				request
+					.patch(Endpoints.CHANNEL(channel.id))
+					.set("authorization", self.token)
+					.send({
+						name : channel.name,
+						position : 0,
+						topic : topic
+					})
+					.end((err, res) => {
+						if(err){
+							reject(err);
+						}else{
+							channel.topic = res.body.topic;
+							resolve();
+						}
+					})
+				
+			}
+			
+		});
+	}
 
 	sendWS(object) {
 		if (this.websocket)