general cmake cleanup

On Fedora we have linux/i2c-dev.h, but it does not hold i2c_smbus_ definitions, so do not try to use it just
because it exists.

https://sourceware.org/glibc/wiki/Release/2.26#Removal_of_.27xlocale.h.27

Use new cmake AgoService macro to create & install systemd files for each service.
Renamed devices/scheduler to schedulerold, since it conflicts with
core/scheduler

This simplifies and normalizes the python based package installations.
Before, each py service was installed in /opt/agocontrol/bin/agoXXX.py.
If there was any other .py libraries to be included, they where also
placed in bin/.

Now we place the entrypoint in bin/agoXXX (without .py), as a symlink
which points to python/agoXXX/agoXXX.py. Any extra python files for
agoXXX are now placed in this python/agoXXX directory as well, avoiding
global polution in the bin/ dir.

Updated initscripts & debian control files with new paths
Should make them templated instead..

On FreeBSD _ZN5boost6chrono12steady_clock3nowEv was not found

Add proper threading library dependency (typically pthread), was not
included properly on raspbian.
Also bump to minimum CMake 3.0, should be satisfied everywhere.

Support for jsoncpp differs wildly between distributions. jsoncpp is
small and has support for "amalgamated" version to be included in
applications.

To execute tests, make sure cppunit is installed, then run either
'ctest' or 'make check'. The former just runs the compiled tests, the
second is a custom make target which also ensures the proper files are
built before tests are executed (also, defaults to more verbose output).

If Boost.Log is found, we use that.
Else, we fall back to a simpler hack which outputs simple log message.

Set -Wall for all pieces, devices too, to encourage proper coding. -Werror on core/shared only though.

New agocontrol::getConfigPath() to shared/agoclient.h allows
for dynamic setting of configuration path instead of a compile-time
CONFDIR define.

Default configuration path is still controlled via cmake CONFDIR var,
but env var AGO_CONFDIR can be set to override this.

Similar setup exists for getLocalStatePath(), with AGO_LOCALSTATEDIR env var.

Fixed all occurences in all devices, but agodmx/knx have not been tested
due to missing deps (simple changes though, so should be good).

Also added extra load_path to Augeas, so it can look for the lens
definition in the conf/ dir, if not installed globally.