neads cleanup

exclude parts that have different default values

Security component adjustments: fixed comment style, hkdf() and pbkdf2() are now protected, compareString() is now public

Fixes #4114: Added Security::generateRandomHexKey(), used it for various tokens and default key generation

- removed unformat methods, they do not belong here
- removed db format, which is also not purpose of this class
- refactored the whole set of methods to be simpler and better
  maintainable

More unit tests needed.

#2359 one test failed in Travis because standard medium date format is different in Travis then on my locale PC.

Improved action filter and action execution flow by supporting installing action filters at controller, module and application levels

Fixed phpdoc, removed unit tests for Formatter asRelativeTime that were relative to current time since it was impossible to specify correct expected values