[Application][Linux] Convert tools to C++

We don't have strong reasons to keep them a C, so to keep consistency
and make use of our lint checks, moving those to C++.

We still use gdbus here (instead of src/dbus) due to it's convenient
sync API (for the case of the tools, this API is OK) and to avoid
needing to integrate appcore/aul with base::MessageLoop.
Merge pull request #1392 from cmarcelo/change-tools-to-cpp

[Application][Linux] Convert tools to C++