Add getter and setter for Content-Type header

Fixes #296
Closes #305

panda/src/downloader/httpChannel.I

@@ -426,6 +426,23 @@ get_max_updates_per_second() const {
   return _max_updates_per_second;
 }
 
+/**
+ * Specifies the Content-Type header, useful for applications that require
+ * different types of content, such as JSON.
+ */
+INLINE void HTTPChannel::
+set_content_type(string content_type) {
+  _content_type = content_type;
+}
+
+/**
+ * Returns the value of the Content-Type header.
+ */
+INLINE string HTTPChannel::
+get_content_type() const {
+  return _content_type;
+}
+
 /**
  * This may be called immediately after a call to get_document() or some
  * related function to specify the expected size of the document we are

panda/src/downloader/httpChannel.cxx

@@ -100,6 +100,7 @@ HTTPChannel(HTTPClient *client) :
   _response_type = RT_none;
   _http_version = _client->get_http_version();
   _http_version_string = _client->get_http_version_string();
+  _content_type = "application/x-www-form-urlencoded";
   _state = S_new;
   _done_state = S_new;
   _started_download = false;
@@ -3624,7 +3625,7 @@ make_header() {
 
   if (!_body.empty()) {
     stream
-      << "Content-Type: application/x-www-form-urlencoded\r\n"
+      << "Content-Type: " << _content_type << "\r\n"
       << "Content-Length: " << _body.length() << "\r\n";
   }
 

panda/src/downloader/httpChannel.h

@@ -143,6 +143,9 @@ PUBLISHED:
   INLINE void set_max_updates_per_second(double max_updates_per_second);
   INLINE double get_max_updates_per_second() const;
 
+  INLINE void set_content_type(string content_type);
+  INLINE string get_content_type() const;
+
   INLINE void set_expected_file_size(size_t file_size);
   streamsize get_file_size() const;
   INLINE bool is_file_size_known() const;
@@ -336,6 +339,7 @@ private:
   string request_path;
   string _header;
   string _body;
+  string _content_type;
   bool _want_ssl;
   bool _proxy_serves_document;
   bool _proxy_tunnel_now;