Added all the headers to FIND_PATH

Findusb_i2c_adapter.cmake

 #edit the following line to add the librarie's header files
-FIND_PATH(usb_i2c_adapter_INCLUDE_DIR usb_i2c.h /usr/include/iri/usb_i2c_adapter /usr/local/include/iri/usb_i2c_adapter)
+FIND_PATH(usb_i2c_adapter_INCLUDE_DIR usb_i2c.h usb_i2c_exceptions.h /usr/include/iri/usb_i2c_adapter /usr/local/include/iri/usb_i2c_adapter)
 
 FIND_LIBRARY(usb_i2c_adapter_LIBRARY
     NAMES usb_i2c_adapter
@@ -20,4 +20,4 @@ ELSE (usb_i2c_adapter_FOUND)
    IF (usb_i2c_adapter_FIND_REQUIRED)
       MESSAGE(FATAL_ERROR "Could not find usb_i2c_adapter")
    ENDIF (usb_i2c_adapter_FIND_REQUIRED)
-ENDIF (usb_i2c_adapter_FOUND)
\ No newline at end of file
+ENDIF (usb_i2c_adapter_FOUND)