A series of improvements:

- Improved Protobuf module compatibility (disabled by default);
- Hide advanced settings;
- Added build tree configuration;
- Added build of examples.

Fix the cmake configuration file install path to be more standards compliant (See the description of cmake's config search behavior on https://cmake.org/cmake/help/v3.4/command/find_package.html)

Additional export as "protobuf" package
for importing from other cmake projects