Add qmlimportscanner.

qmlimportscanner scans for import statements in qml
files and returns a JSON-formatted list of imports.
This is done recursively in order to get all dependencies.

Usage: "qmlimportscanner path/to/app/qml/"
		-importPath path/to/qtbase/qml

Change-Id: I0e99caaf4216058c52a4706f7fdbeaf1eba0bbc1
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>