LoggerConfig::getFor always returns the same instance of Logger for the same $name.

This avoid issues when push handlers/processors to that logger.
Use the Monolog\ErrorHandler to log errors and exceptions.
PHPCI/Logging/Handler becomes PHPCI/ErrorHandler.
And it only throws ErrorException for reported errors.
No need to initialize a second $loggerConfig in daemonise.

Close #892

PHPCI/ErrorHandler.php

@@ -0,0 +1,68 @@
+<?php
+/**
+ * PHPCI - Continuous Integration for PHP
+ *
+ * @copyright    Copyright 2014, Block 8 Limited.
+ * @license      https://github.com/Block8/PHPCI/blob/master/LICENSE.md
+ * @link         https://www.phptesting.org/
+ */
+
+namespace PHPCI;
+
+/**
+ * Error Handler
+ *
+ * @package PHPCI\Logging
+ */
+class ErrorHandler
+{
+    /**
+     * @var array
+     */
+    protected $levels = array(
+        E_WARNING           => 'Warning',
+        E_NOTICE            => 'Notice',
+        E_USER_ERROR        => 'User Error',
+        E_USER_WARNING      => 'User Warning',
+        E_USER_NOTICE       => 'User Notice',
+        E_STRICT            => 'Runtime Notice',
+        E_RECOVERABLE_ERROR => 'Catchable Fatal Error',
+        E_DEPRECATED        => 'Deprecated',
+        E_USER_DEPRECATED   => 'User Deprecated',
+    );
+
+    /**
+     * Registers an instance of the error handler to throw ErrorException.
+     */
+    public static function register()
+    {
+        $handler = new static();
+        set_error_handler(array($handler, 'handleError'));
+    }
+
+    /**
+     * @param integer $level
+     * @param string  $message
+     * @param string  $file
+     * @param integer $line
+     *
+     * @throws \ErrorException
+     *
+     * @internal
+     */
+    public function handleError($level, $message, $file, $line)
+    {
+        if (error_reporting() & $level === 0) {
+            return;
+        }
+
+        $exceptionLevel = isset($this->levels[$level]) ? $this->levels[$level] : $level;
+        throw new \ErrorException(
+            sprintf('%s: %s in %s line %d', $exceptionLevel, $message, $file, $line),
+            0,
+            $level,
+            $file,
+            $line
+        );
+    }
+}