MXS-1300: Un-modularize the core

Making the core a module proved to bring more problems than it solved. For
the sake of simplicity in installation and code coverage reporting, the
core is now completely contained in the `lib/` directory.

Also added preliminary coverage reporting with nyc.

maxctrl/lib/rotate.js

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2020-01-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+require('./common.js')()
+
+exports.command = 'rotate <command>'
+exports.desc = 'Rotate log files'
+exports.handler = function() {}
+exports.builder = function(yargs) {
+    yargs
+        .command('logs', 'Rotate log files by closing and reopening the files', {}, function(argv) {
+            maxctrl(argv, function(host){
+                return doRequest(host, 'maxscale/logs/flush/', null, {method: 'POST'})
+            })
+        })
+        .usage('Usage: rotate <command>')
+        .help()
+        .command('*', 'the default command', {}, () => {
+            logger.log('Unknown command. See output of `help rotate` for a list of commands.')
+        })
+}