Added RADIUS support

Add RADIUS module that can run on CentOS only with
EPEL packages using Config:IniFiles to read more
sophisticated configurations.

Closes #14
Add client machine definition to modell

Added 3 new tables:
* ClientMachine
* MachineToken
* MachineOptions

added the API to add and remove machines and
add and remove tokens to machines.

At the moment we can just run the functional tests: test_machine.py

Working on #10
Merge branch 'master' of github.com:privacyidea/privacyidea