BUG: Fix Qt5 continuous integration

This commit will fix the following error:

```
[ 65%] Building CXX object Libs/Widgets/Plugins/CMakeFiles/CTKWidgetsPlugins.dir/ctkWidgetsPlugins.cpp.o
In file included from /usr/src/CTK/Libs/Widgets/Plugins/ctkWidgetsPlugins.cpp:25:0:
/usr/src/CTK/Libs/Widgets/Plugins/ctkWidgetsPlugins.h:29:63: fatal error: QtUiPlugin/QDesignerCustomWidgetCollectionInterface: No such file or directory
 #include <QtUiPlugin/QDesignerCustomWidgetCollectionInterface>
                                                               ^
compilation terminated.

[...]

In file included from /usr/src/CTK-build/CTK-build/Libs/Widgets/Plugins/moc_ctkWidgetsPlugins.cpp:9:0:
/usr/src/CTK-build/CTK-build/Libs/Widgets/Plugins/../../../../../CTK/Libs/Widgets/Plugins/ctkWidgetsPlugins.h:29:63: fatal error: QtUiPlugin/QDesignerCustomWidgetCollectionInterface: No such file or directory
 #include <QtUiPlugin/QDesignerCustomWidgetCollectionInterface>
                                                               ^
compilation terminated.
```

CMake/CircleCI/Dockerfile-qt5

@@ -10,6 +10,9 @@ RUN apt-get update && apt-get install -y \
   wget && \
   rm -rf /var/lib/apt/lists/*
 
+# Allow code written for more recent Qt version to compile
+RUN cp -r  /usr/include/x86_64-linux-gnu/qt5/QtDesigner/ /usr/include/x86_64-linux-gnu/qt5/QtUiPlugin
+
 RUN wget https://cmake.org/files/v3.7/cmake-3.7.1-Linux-x86_64.tar.gz && \
   tar -xzf cmake-3.7.1-Linux-x86_64.tar.gz && \
   rsync -avz cmake-3.7.1-Linux-x86_64/ /usr/local