Refactor Actuators

Refactor Actuators

Done fairly similar to Sensors now. Included the LED test and a new test that just writes to a file.
`tail -f` the file and change the control to see how Actuator_Loop automagically does its job.

New features / Notes:
 - ActuatorControl is a simple step increase (not just a single value) which Actuator_Loop automatically follows
   - That required very small changes :)
 - Control_Handler no longer checks for key (since that's passed as a cookie)
   - Will want to look at preventing different users from stopping an experiment in progress (by preventing them from logging in entirely?)
   - Will probably want to look at implementing "admin" and "regular" users, or at least providing the basis for it in the server
 - Can change sensor sampling rate through api
   - May want to look at implementing an "average over time period" to reduce the load on the client
     - eg: Sensor records at a sampling rate << 1s, but only records a DataPoint (average) every second
 - Actuators have a Sanity Check function; do something similar for Sensors?
   - Will want to look at safety stuff more carefully, since at the moment things just call "Fatal"
     - This should in turn call "Cleanup" which should in turn deinitialise any active Sensors/Actuators
     - Perhaps we need "Fatal" and "Reset" to give different return codes, and then ./run.sh will restart depending on the return code

Looking at getting values plotted against values (instead of time).
  - For each time stamp on the dependent variable, take the independent variable with time stamps between it and the next, then average
    - Seems reasonable, not sure whether to do in server or client though, will write something to test the algorithm first.

Things are getting there, but still a lot to do.

I just realised I temporarily uncommented security in fastcgi.c
... It's a good thing the system still hasn't been deployed, because I can't be bothered changing it back at the moment.