Use fewer lines to assign post/query params.
Allow requestAction() to set environment values.

Use the environment extra key to provide environment/header value
overrides.

Refs #3566
Add doc block example.
Simplify View blocks.

This set of changes breaks the existing behavior of blocks in a few
ways, but leaves us with a simpler and easier to reason about API. It
also solves weird behavior with prepend() where it wouldn't prepend at
all.

* startIfEmpty() is removed, as that behavior is not relevant when
  blocks always overwrite.
* append() and prepend() no longer have capturing modes. They can only
  be used to append/prepend content into blocks. The capturing mode of
  prepend never worked so I dobut anyone will miss this.
* Additional tests were added for the new behavior.

Refs #3561
ORM\Associations: Add removeAll() method

Useful in cases where you want to rebind associations manually.
Merge pull request #3627 from rchavik/3.0-associations-remove-all

ORM\Associations: Add removeAll() method
Merge pull request #3618 from cakephp/3.0-requestaction-environment

3.0 requestaction environment
Removing crazy method in Security class
Re-implementing SimplePasswordHasher to use the more secure
password_hash function

Also requiring a compatible php library for password_hash for users on
version < 5.5
Unifying BlowfishPasswordHasher and deprecating it in favor of Simple

This will make it easier for people migrating to 3.0
Adding a test case where showing a rejection of a password
Simplifying needsRehash signature and adding tests
Adding WeakPasswordHasher as a substitute for the old Simple one

This will help pepople not get completely stranded when migrating to
3.0, a future change will be introduced to help them migrate their
existing database of users.
Extracting the password hashing builder to a factory object
Implementing a FallbackPassword hasher to assist people in migrating
users to a stronger password algorithm
Bugfixing and testing FallbackPasswordHasher
Implemented FallbackPasswordHasher::needsRehash()
Solving a few problems found in code review
Fixing CS problems
Fixed another CS problem