Release v2.0-20180123

Changes in v2.0-20180123 (since v2.0-20180122):

ESPEasy release bot (1):
      automaticly updated release notes for v2.0-20180123

Edwin Eefting (5):
      test suite: now possible to run all tests at once. fixes
      test suite: espcli can now do stuff for all configured nodes
      clear custom task and controller settings when selecting a different device or protocol. replaces #762 . fixes #721
      added easy reboot warning and function to work around several issues
      request mainpage when checking if reboot is complete

Gijs Noorlander (1):
      Central function for system variable replacement (#757)