Update docs blocks.
Move ConnectionManager to Database namespace

This puts it closer to the Connection objects it manages.
Move checks closer to the side effects.

Check classnames and enabled() closer to where they are constructed. This
makes driver() safer when used outside of a constructor as well.
Refactor away configKeyName.

Replace it with a method that reads from constructor configuration
parameters. The new name option will be supplied by ConnectionManager.
Update tests to use new ConnectionManager.

Update tests to use the new API's in ConnectionManager.
Update & streamline ConnectionManager

ConnectionManager now uses the Registry object system created earlier to
create and manage connection + driver pairs. The temporary code that
lived in old ConnectionManager is now part of this code. If/When a more
formal datasource interface is created it should be simple to adapt this
code.

Many of the old goofy method names have been removed and replace with
simpler more consistent method names. The test suite has been updated as
well. Both `create()` and `getDataSource()` have been left behind as
aliases/wrappers for other methods as I feel they are the most commonly
used methods in ConnectionManager.
Update other tests referencing ConnectionManager.
Update default config file.
Update doc blocks and expand tests.
Fix coding standards errors.
Merge pull request #1551 from markstory/3.0-connectionmanager

3.0 update connection manager