Fix installation of most examples

* Make sure the example source code is installed
* Make sure the installation path is consistent with the path within the module, to ensure
  that the sources end up next to the compiled binary.
* Skip the widgets nano browser from the installation, as it's a developer tool.

Change-Id: I35b421e12f8e6ddd3f2045e318b21543ff929cd8
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>