HTTP Server : Default content type of response should be HTTPD_TYPE_TEXT

Closes https://github.com/espressif/esp-idf/issues/2527

components/http_server/src/httpd_parse.c

@@ -567,7 +567,7 @@ esp_err_t httpd_req_new(struct httpd_data *hd, struct sock_db *sd)
     ra->sd = sd;
     /* Set defaults */
     ra->status = (char *)HTTPD_200;
-    ra->content_type = (char *)HTTPD_TYPE_JSON;
+    ra->content_type = (char *)HTTPD_TYPE_TEXT;
     ra->first_chunk_sent = false;
     /* Copy session info to the request */
     r->sess_ctx = sd->ctx;

examples/protocols/http_server/advanced_tests/scripts/test.py

@@ -341,7 +341,7 @@ def get_hello(dut, port):
     if not test_val("data", "Hello World!", resp.read().decode()):
         conn.close()
         return False
-    if not test_val("data", "application/json", resp.getheader('Content-Type')):
+    if not test_val("data", "text/html", resp.getheader('Content-Type')):
         conn.close()
         return False
     Utility.console_log("Success")