fix Ldap converter serialize test

Starting from PHP versions 5.4.30, 5.5.14 and 5.6.0beta4, the serialized
representation of a DateTime includes fractional seconds.
The data provider must check the PHP version and provide a correct
serialized representation of the DateTime object.

refs #6468
fix Atom tests with fractional seconds in dates

the DateTime object is correctly created in Extension\Atom\Entry#L173,
but the tests created the comparison DateTime with the wrong format (ISO8601)
and the wrong datetime string (did not include the fractional seconds)
remove conditional in dataProvider and replace with serialized object
Allow running php-cs-fixer in parallel

A recent change in php-cs-fixer has led to massive performance issues, leading
to timeouts of ZF2 builds. This change is a band-aid, and does the following:

- Alters the php-cs-fixer configuration to remove the lines that excluded
  top-level paths, and added paths to test. This means you cannot just run
  "php-cs-fixer" in the root anymore; you **must** pass a directory in which to
  run the checks.
- Alters the Travis-CI configuration to list the directories in which to run
  php-cs-fixer and pass them to the `parallel` command.

The changes ensure that output will occur periodically. The checks run
_somewhat_ faster, though the performance improvement is certainly less than
50%.
Switched to known good revision of php-cs-fixer

- Determined from last build that did not have CS errors flagged.
Updated php-cs-fixer rules

- Path restrictions must be specified differently when you pass the path to a
  component via the CLI as an argument to php-cs-fixer; they become relative to
  the argument, not the project root.
Re-instated two notPath() rules
Merge branch 'hotfix/#6671-fixed-parallelized-cs-checks'

Close #6671
Merge pull request #6610 from gkralik/fix/travis-failing-tests

Fix travis failing tests
Merge branch 'hotfix/6610'

Close #6610
PHPCS fixes for Zend\Valiator