simple design for mechanized home automation devices to stop at limits
Many commercial systems of this type use a system similar to what is used in garage door openers. This is a screw mechanism that is driven by the motor at the same time as the actual output drive.

There are adjustable limit switches that trip when the screw reaches arbitrary points.

Because this mechanism is completely contained in the motor drive enclosure, there aren't any external limit switches required. Thus - no external wires for the limit switches. 

Kinda hard to explain without pictures. Google will give you some guidance.

[Edit]

Here is a short video from Google that shows such a mechanism in a Craftsman Garage Door Opener.  Notice that the central screw has a traveller that moves from one end to the other.  The adjustment screws move the limit switches either forward or backwards to set the location where the traveller meets the switches.
Craftsman Garage Door Opener

[Edit 2]

Here is an expired patent of a similar system but with two separate travellers.  This may be easier for you to fabricate a DIY version.  Patent via Google