Introduced a CONFIG option that enables declarative debug services

Introduced a CONFIG option that enables declarative debug services

This replaces the need for applications to explicitly make a call to
enable the debug services, and rather does it in declarative.h when the
'declarative_debug' CONFIG option is used.

Done-with: Kai Koehne
Reviewed-by: Martin Jones
Reviewed-by: Michael Brasser
(cherry picked from commit 5517cc588c39814530b8bfd957821f55be42acf2)

Change-Id: Iacfc5a9b2ca0c2610288cf86f190b4a9950cacd1
Reviewed-on: http://codereview.qt.nokia.com/2436
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Martin Jones <martin.jones@nokia.com>