Fix incorrect value in PaginatorHelper::counter()

Now that limit is conditionally defined to only exist when the limit is
different than the default, a second perPage key is needed to correctly
generate counter() output.

Fixes #3419
Merge pull request #3420 from cakephp/issue-3419

Fix incorrect value in PaginatorHelper::counter()
Fix TableRegistry::get() and plugin classnames.

Fix issues around using `className` option with Plugin.Class forms.
Also fix registry key issues where get('Plugin.Comments') and
get('Comments') would result in different instances.

Fixes #3425
Merge pull request #3430 from cakephp/issue-3425

Fix TableRegistry::get() and plugin classnames.
Synchronize docblocks.
Tweak Validator API to be more user friendly.

Using `allowEmpty('field', false);` doesn't read as well as
`notEmpty('field)`. I feel the mode will be less frequently used over
setting a custom message, so switch the order of those parameters
around.
Update bake generated code to use new validator api.
merge fields and blacklist

rather than have an explicit blacklist - blacklist a field by
specifying it as false in $fields
test corrections
Add mode to notEmpty() and remove message from allowEmpty().

Having `$message` for allowEmpty() doesn't make sense as it will only
remove validation errors now, not cause them to be triggered. Add
`$mode` to notEmpty() as it is very relevant there.
Expand unit tests and fix issue with notEmpty().
Add additional tests for intersection of notEmpty()/allowEmpty()
Merge pull request #3435 from markstory/3.0-validation-tweaks

RFC - 3.0 validation tweaks
add a test that the "blacklist" does something
Merge pull request #3436 from AD7six/3.0-form-inputs-blacklist

RFC: merge blacklist and fields for Form::inputs
Stricter string comparisons.
More coding standard corrections.
Fix travis builds.

Travis updated to phpunit 4 for PHP 5.3 and CakePHP needs phpunit 3.7.
This is a hotfix for TextHelper which seems to have gone wrong in a merge. tail() is missing completly and the docs for truncate() are the ones for tail(). This fixes it.
Correct documentation.