Modify CakeSocket and HttpSocket so that the "protocol" parameter can be used to specify which protocol to use for creating sockets. These are protcols in the php "[a-z]://" wrapper sense. I also modified the test for these two files respectively to accomodate these new changes.
Unrelated to this bug, I added a "head" function inside of HttpSocket to go along with the GET/POST/PUT/DELETE/PATCH combination that's already present. Came in handy for me for deciding if I wanted to hit a resource with HttpSocket or not.
Fix coding standard violations
Remove unneeded comment out line that I just saw in compare view on GH
Fix HttpSocket test to actually reset protocols for correct test. Modify HttpSocket so that Https with non-passed in protocol doesn't set it to tcp and fail test.
Test for new HEAD function inside HttpSocket
Fix spacing to conform to coding standards
Add support for persistent SMTP connections.
Simplify tests, fix CS, remove `autoDisconnect` option.
Make `connect()` invoke authentication, make tests more explicit, add more tests.
Make SMTP auth reply code checks work properly.
Add some more exception message checks
Add `.` to the list of allowed characters.

This was missed when the email validation rules were relaxed in
dc34d80f6f622e883b8c7db9ef489bd514c8701f.

Fixes #4027
Remove CacheHelper and related features.

CacheHelper is going to be split into a stanalone plugin for 3.x.
Removing this code will reduce confusion in the future about how to do
caching.
Fix build failures.

The recent Query->join() changes contained an invalid column name, and
the changes to EntityContext necessitated changes in the tests to
reflect what should have always been reality.
Add note about identifier quoting in pdo error template.

Hopefully that should avoid a few unnecessary tickets.
Merge pull request #4030 from ADmad/3.0-pdo-error-msg

Add note about identifier quoting in pdo error template.
Merge pull request #4029 from cakephp/build-fix

Fix build failures.
Remove dead code in test stub.

This code does not work and will trigger notice errors if it was
actually run.
Singularize names in 'New' links in bake templates
Merge pull request #4041 from bcrowe/3.0-bake-template

3.0 - Singularize names in 'New' links in bake templates