Updated RegexFilter to accept events by default upon match

Accepting events by default is more in line with the way regular
filter functions work. This behavior can be overridden when the
filter is created.
No fake context-wide filter created by default

The LoggerContext created a fake accept-all context-wide filter but
that's no longer needed.
Filters created during initialization. Ready for testing

Filters referenced in the configuration are created when Woodman is
initialized. The configuration may reference context-wide filters,
logger filters or appender filters. Each configuration may either be
an array or an object indexed by the filter's type.

Example of a context-wide filter using an array:
  {
    "filters": [
      {
        "type": "RegexFilter",
        "regex": "Hello"
      }
    ],
    "appenders": [...],
    "loggers": [...]
  }

Same example with an object:
  {
    "filters": {
      "RegexFilter": {
        "regex": "Hello"
      }
    },
    "appenders": [...],
    "loggers": [...]
  }

Code is ready for testing but has not been tested yet.