create lib for getting api key token from request

lib/cartodb/api/get_api_key_token_from_request.js

@@ -0,0 +1,62 @@
+'use strict';
+
+const basicAuth = require('basic-auth');
+
+module.exports = function getApiKeyTokenFromRequest(req) {
+    let apiKeyToken = null;
+
+    for (var getter of apiKeyGetters) {
+        (apiKeyToken = getter(req));
+        if (apiKeyTokenFound(apiKeyToken)) {
+            break;
+        }
+    }
+
+    return apiKeyToken;
+};
+
+//--------------------------------------------------------------------------------
+
+const apiKeyGetters = [
+    getApikeyTokenFromHeaderAuthorization,
+    getApikeyTokenFromRequestQueryString,
+    getApikeyTokenFromRequestBody,
+];
+
+function getApikeyTokenFromHeaderAuthorization(req) {
+    const credentials = basicAuth(req);
+    
+    if (credentials) {
+        return credentials.pass;
+    } else {
+        return null;
+    }
+}
+
+function getApikeyTokenFromRequestQueryString(req) {
+    if (req.query.api_key) {
+        return req.query.api_key;
+    }
+
+    if (req.query.map_key) {
+        return req.query.map_key;
+    }
+
+    return null;
+}
+
+function getApikeyTokenFromRequestBody(req) {
+    if (req.body && req.body.api_key) {
+        return req.body.api_key;
+    }
+
+    if (req.body && req.body.map_key) {
+        return req.body.map_key;
+    }
+
+    return null;
+}
+
+function apiKeyTokenFound(apiKeyToken) {
+    return !!apiKeyToken;
+}