Credit Kitware and csimsoft for their maintenance roles

Add maintenance credit to command-line "--version" output and the
cmake-gui "About" dialog.
Credit the Qt Project as licenced under LGPLv2.1 for cmake-gui

Extract LICENSE.LGPL from https://git.gitorious.org/qt/qt5.git
commit ecd64f62 (Add license files mandated by (L)GPL, 2013-05-29).
Remove trailing whitespace and blank lines from the end of the file.
Place it as Licenses/Qt/LICENSE.LGPL within our source tree.  When
the cmake-gui is built, install the license file under CMAKE_ROOT.

Teach cmake-gui to display the Qt copyright and the path to the
licence file in its "About" dialog.
Merge topic 'cmake-credits' into next

623f410 Credit the Qt Project as licenced under LGPLv2.1 for cmake-gui
6fc4ab9 Credit Kitware and csimsoft for their maintenance roles