Fix `fix` command to handle `--fixers` option when contains include and excluding fixers
FixersResolver - simplify code
Fix README and some codes.
FixersResolver - make class more state aware and enhance it's tests
feature #599 Fix `fix` command to handle `--fixers` option when contains extra and excluding fixers (fivestar, keradus)

This PR was merged into the 1.0.x-dev branch.

Discussion
----------

Fix `fix` command to handle `--fixers` option when contains extra and excluding fixers

Currently, when `--fixers` option contains extra and excluding mixed filters such as `-eol_ending,concat_with_spaces`, excluding filter will be enabled, however, extra filter will not be enabled.

This PR fixes this behavior, so enable both type filters when mixed filters given.

----

`sample.php`

```php
<?php
echo 'foo'.'bar', PHP_EOL;

```

Current version: (`concat_with_spaces` is not enabled)

```
% php-cs-fixer fix -v --diff --fixers="-eol_ending,concat_with_spaces" --dry-run sample.php
   1) /home/fivestar/sample.php (eof_ending)
      ---------- begin diff ----------
      --- Original
      +++ New
      @@ @@
       <?php
       echo 'foo'.'bar', PHP_EOL;

      -

      ---------- end diff ----------
```

Fixed version: (`concat_with_spaces` is enabled)

```
% php-cs-fixer fix -v --diff --fixers="-eol_ending,concat_with_spaces" --dry-run sample.php
   1) /home/fivestar/sample.php (eof_ending, concat_with_spaces)
      ---------- begin diff ----------
      --- Original
      +++ New
      @@ @@
       <?php
      -echo 'foo'.'bar', PHP_EOL;
      -
      +echo 'foo' . 'bar', PHP_EOL;

      ---------- end diff ----------
```

Commits
-------

23c07bb FixersResolver - make class more state aware and enhance it's tests
e75c985 Fix README and some codes.
6876726 FixersResolver - simplify code
f3c966f Fix `fix` command to handle `--fixers` option when contains include and excluding fixers