Some missing base unit tests

When translation is missing source language should be used for formatting

This reverts commit c94131b8.

fixed configs

check error level in error handler

Update error.md

typo fix

Fixes #2054: Added support for using custom application configuration with the console command runner

need to confirm the exception properties in Yii 2

Feature/toolbar ui 2

Fixes #2341, fixes #2317: moved codeception dependecies to "suggest" section, fixed codeception version on stable branch

issue yiisoft/yii2-coding-standards#4