[#4624] Fix notice

- Factory embedded in ViewHelperManagerFactory was not checking if
  services and/or array keys existed prior to accessing them.
[#4629] Allow caching null values from callbacks

- Implemented test case for #4629
- Used fix suggested in original report
Allow specifying router class to use

- Allows usage of TranslatorAwareTreeRouteStack via configuration now:

  'router' => array(
      'route_class' => 'Zend\Mvc\Router\Http\TranslatorAwareTreeRouteStack',
      'routes' => array( /* ... */ )
  )

- Also possible to use alternate console routers this way
Incorporate feedback
Incorporate feedback

- via @mwillbanks on IRC
Merge branch 'hotfix/route-translation-config' of git://github.com/weierophinney/zf2 into hotfix/4630
Merge branch 'hotfix/4630'

Close #4630
[#4624] Created test for fix

- Adds new test suite for ViewHelperManagerFactory, and adds test for
  specific fix from this PR.
[#4624] Added more tests

- Used a data provider to allow testing the three various inputs that
  led to issues previously.
Merge branch 'hotfix/4624' of git://github.com/weierophinney/zf2 into hotfix/4624
Merge branch 'hotfix/4624'

Close #4624
Zend\Paginator\Adapter\DbSelect
First attempt at using subselect to calculate full count
Merge branch 'hotfix/4629' of git://github.com/weierophinney/zf2 into hotfix/4629
Merge branch 'hotfix/4629'

Close #4629
Zend\Db & Zend\Paginator
- Paginator: removed clearing of columns from select
- Db\Sql\Select: when resettings columns, reset value should be array(self::SQL_STAR)
Zend\Paginator - added tests for DbSelect
Zend\Db\Sql\Select - reverted reset on column
Zend\Paginator
- reorganized the Mock setup for getItems and count tests to work
Merge branch 'hotfix/paginator-db-count-subselect' of https://github.com/ralphschindler/zf2

PR #4641
Closes #4590
Closes #3647
[2.2.1] release readiness

- Updated VERSION
- Updated README
- Updated CHANGELOG
Merge branch 'releases/2.2.1'

2.2.1 readiness