Implemented utility method to validate uniqueness of a field
Fix datetime fields not being secured.

Ensure all the various datetime fields are added to Form->fields so they
are not blackholed later.

Fixes #3573
Add another test for secure option + datetime fields.

Refs #3573
Accept older blowfish hashes.

Both `2a` and `2x` are valid types of blowfish hashes, that while being
older should be accepted.
Fix an issue where custom Auth config would cause errors.

When the params key is omitted from the AuthComponent config a fatal
error would happen.
Merge pull request #3575 from cakephp/3.0-security-hash

3.0 - Accept older blowfish hashes.
Merge pull request #3572 from cakephp/3.0-table-is-unique

3.0 table isUnique
Consistent use of `Shell::err` for errors
Merge pull request #3577 from tersmitten/consistent-use-of-err-for-errors

Consistent use of `Shell::err` for errors
Fix docblock CS errors.
CS fixes.
Fixes bug described in #3581

Routes with '/**' are now correctly handled when called by
$this->Html->link() in a view.
Revert "Fixes bug described in #3581"

This reverts commit 6c75e3697d5b0d70ed0cc73403b16d2812bd02ad.
Fixes bug described in #3581

Routes with '/**' are now correctly handled by the HtmlHelper->link()
More docblock CS fixes.
Merge pull request #3580 from cakephp/3.0-cs-fixes

Fix docblock CS errors.
Baking uniqueness rules for email and username fields automatically
Adding test for generating unique validaiton rule for a username field
Revert "Fixes bug described in #3581"

This reverts commit e6c6e0bf2c541885f890968d6047974d587a422e.
Fixes bug #3581

Fixes bug #3581 and the issue noticed by markstory