MXS-1220: Add versioned URLs

Added versioning to URLs. This should allow somewhat safe modification to
the API after it has been finished.

server/core/maxscale/httprequest.hh

@@ -26,6 +26,9 @@
 
 #include "http.hh"
 
+// The API version part of the URL
+#define MXS_REST_API_VERSION "v1"
+
 static int value_iterator(void *cls,
                           enum MHD_ValueKind kind,
                           const char *key,
@@ -160,6 +163,14 @@ public:
     {
         return m_hostname.c_str();
     }
+
+    /**
+     * @brief Drop the API version prefix
+     *
+     * @return True if prefix is present and was successfully removed
+     */
+    bool validate_api_version();
+
 private:
 
     /** Constants */
@@ -173,5 +184,5 @@ private:
     std::deque<std::string>            m_resource_parts; /**< @c m_resource split into parts */
     std::string                        m_verb;           /**< Request method */
     std::string                        m_hostname;       /**< The value of the Host header */
-    struct MHD_Connection* m_connection;
+    struct MHD_Connection*             m_connection;
 };

server/core/maxscale/httpresponse.hh

@@ -30,6 +30,7 @@
 #define HTTP_RESPONSE_HEADER_LAST_MODIFIED "Last-Modified"
 #define HTTP_RESPONSE_HEADER_ETAG          "ETag"
 #define HTTP_RESPONSE_HEADER_ACCEPT        "Accept"
+#define HTTP_RESPONSE_HEADER_CONTENT_TYPE  "Content-Type"
 
 typedef std::map<std::string, std::string> Headers;