Skip logic in PeriodicTrigger mainLoop for TestableMode

Do not rely on EntityOwner for accessig Application object.

- renamed timeout to period.
- introduced PeriodicTrigger::sendTrigger
- mainloop logic bypassed on startup if owner application is in testable
  mode.

fix for new boost versions (boost::fusion::for_each() changed, second argument by default no longer a reference, so we have to specifiy that explicitly)

This reverts commit 7eace484.

GNUInstallDirs doesn't really deliver the intended directories. CMAKE_INSTALL_LIBDIR e.g. points to lib/x86_64-linux-gnu on Ubuntu 16.04

- Timeout is now in milliseconds to allow more flexibility
- Default timout can be specified in the constructor
- Make sure the time interval is perfectly matched by using sleep_until instead of sleep_for

Not adding the repository as a remote simply makes it impossible to push
to it. Also this makes it mandatory to always fetch the changes from the
remote anyway since it is not locally mirrored.

- Make data decimation configurable
- Addded some documentation
- Some code cleaning (eliminate warnings, move internal classes into detail namespace)