CMake: Bump CMake minimum version to 3.5
CMake: Bump CMake minimum version to 3.5

Reviewers: #kde_telepathy, apol, heikobecker

Reviewed By: heikobecker

Tags: #kde_telepathy

Differential Revision: https://phabricator.kde.org/D24103

KDE/telepathy-logger-qt,KDE/telepathy-logger-qt,KDE/telepathy-logger-qt