Use GNUInstallDirs instead of HawaiiInstallDirs

We don't need Vibe anymore so we use HawaiiInstallDirs.
Use FeatureSummary instead of MacroLogFeature

Produces a better output and is shipped with CMake.
Require Qt 5.1+
Fix desktop entry installation

Change installation path since we are no longer using HawaiiInstallDirs.