Add DSN parsing support to the Cache class
Fix PHPCS break
Use upper-case DSN everywhere
Remove extra single quote
Switch Database and Cache libraries from `login` to `username`

This unifies the name we give to the `username` key across all classes within CakePHP.
Simplify usage of parseDsn

parseDsn can now be used mostly out of the box by all classes using the StaticConfigTrait - with the exception of ConnectionManager, as noted below. Unless they are otherwise specified, the `scheme` of the DSN is set as both the `className` and `driver`. As such, the preferred method for usage in your application would be:

    Fully\Namespaced\ClassName://username:password@host:port/path?query=string&args=here&driver=Some\Other\Class\Name

This commit drops support for `scheme+Namespaced\ClassName\As\Driver`, simplifying the underlying logic a bit.

For the ConnectionManager class, Drivers still need to transform the path into a database_name, and as such we cannot use the trait method as is.
Working getClassMap() changes
Fix PHPCS violations
Only accept strings in parseDsn
make it possible to modify the dsn class map

Use a static property, and put a get/set method for it into the static
config trait.
Merge remote-tracking branch 'origin/3.0' into 3.0-dsn-support

* origin/3.0: (172 commits)
  Consolidate doc block headings.
  Adding a test for https://github.com/cakephp/cakephp/pull/5019 the plugin view file path
  Fixing the view file loading for plugins in View/View.php
  Make method name better represent what it is going to do.
  Don't mutate cwd.
  More doc block corrections.
  Cosolidate doc block headers
  Add FlashComponent property to PHPDoc for Controller class
  Fix doubly inflected variable names in controller task.
  Use chdir() instead of calling multiple commands.
  Add missing 'b' to radio docs
  Fix FormHelper::radio() options docs
  Add test case for quoted strings
  Fix issue in PoFileParser where only slashes from translations of type array are stripped.
  Remove for attributes for other group type inputs.
  Remove meaningless and possibly wrong for attr.
  Fix missing label elements in input(type=radio)
  Fix radio widget and label=false.
  Fix input() making multiple checkboxes.
  Not using union, but OR conditions
  ...
Adding exception for when login is passed instead of username in Memcached
Added temporary exception for warning users of the change from login => username
Cleanup - Unused local variables
Cleanup - Undefined classes