Added Custom Header Example (arduino-libraries#20)

Added the example posted in arduino-libraries#12 to close the PR. Tested and it works

Author: agdl

examples/CustomHeader/CustomHeader.ino

@@ -0,0 +1,91 @@
+/*
+  Custom request header example for the ArduinoHttpClient
+  library. This example sends a GET and a POST request with a custom header every 5 seconds.
+
+  note: WiFi SSID and password are stored in config.h file.
+  If it is not present, add a new tab, call it "config.h"
+  and add the following variables:
+  char ssid[] = "ssid";     //  your network SSID (name)
+  char pass[] = "password"; // your network password
+
+  based on SimpleGet example by Tom Igoe
+  header modifications by Todd Treece
+
+  this example is in the public domain
+ */
+ 
+#include <ArduinoHttpClient.h>
+#include <WiFi101.h>
+#include "config.h"
+
+char serverAddress[] = "192.168.0.3";  // server address
+int port = 8080;
+
+WiFiClient wifi;
+HttpClient client = HttpClient(wifi, serverAddress, port);
+int status = WL_IDLE_STATUS;
+String response;
+int statusCode = 0;
+
+void setup() {
+  Serial.begin(9600);
+  while ( status != WL_CONNECTED) {
+    Serial.print("Attempting to connect to Network named: ");
+    Serial.println(ssid);                   // print the network name (SSID);
+
+    // Connect to WPA/WPA2 network:
+    status = WiFi.begin(ssid, pass);
+  }
+
+  // print the SSID of the network you're attached to:
+  Serial.print("SSID: ");
+  Serial.println(WiFi.SSID());
+
+  // print your WiFi shield's IP address:
+  IPAddress ip = WiFi.localIP();
+  Serial.print("IP Address: ");
+  Serial.println(ip);
+}
+
+void loop() {
+
+  Serial.println("making GET request");
+  client.beginRequest();
+  client.get("/");
+  client.sendHeader("X-CUSTOM-HEADER", "custom_value");
+  client.endRequest();
+
+  // read the status code and body of the response
+  statusCode = client.responseStatusCode();
+  response = client.responseBody();
+
+  Serial.print("GET Status code: ");
+  Serial.println(statusCode);
+  Serial.print("GET Response: ");
+  Serial.println(response);
+
+  Serial.println("Wait five seconds");
+  delay(5000);
+
+  Serial.println("making POST request");
+  String postData = "name=Alice&age=12";
+  client.beginRequest();
+  client.post("/");
+  client.sendHeader(HTTP_HEADER_CONTENT_TYPE, "application/x-www-form-urlencoded");
+  client.sendHeader(HTTP_HEADER_CONTENT_LENGTH, postData.length());
+  client.sendHeader("X-CUSTOM-HEADER", "custom_value");
+  client.endRequest();
+  client.write((const byte*)postData.c_str(), postData.length());
+
+  // read the status code and body of the response
+  statusCode = client.responseStatusCode();
+  response = client.responseBody();
+
+  Serial.print("POST Status code: ");
+  Serial.println(statusCode);
+  Serial.print("POST Response: ");
+  Serial.println(response);
+
+  Serial.println("Wait five seconds");
+  delay(5000);
+}

examples/CustomHeader/config.h

@@ -0,0 +1,3 @@
+char ssid[] = "ssid";     //  your network SSID (name)
+char pass[] = "password"; // your network password
+