Add coloring for log files with simple layout.

Logs in format:

  <datetime> |
  (TRACE|DEBUG|INFO|WARNING|ERROR|FATAL|STARTED|FAILED|SUCCEEDED|SKIPPED|SCREENSHOT)
  | <message>

are recoginezed and colored (every level with different collor and for
every level message is colored with different shade of gray.

Syntax can be improved to support more variations of log files.