Implemented Non Linear Least Squares Trilateration

Implemented a new class, TrilateratorNoisy2DLeastSquares. This class
makes use of Octave to trilaterate results with a non-linear least
squares numerical analysis.

The SensorServer now requires Octave to be installed, and the optim
package for Octave to be installed as well.

New INI fields:
TRILATERATOR_NOISY_2D_LEAST_SQUARES_GROUPING_THRESHOLD - Same as
grouping threshold for normal Noisy 2D trilaterator
SENSOR_SERVER_OCTAVE_BINARY_PATH - Path to the binary of Octave, default
on Windows is C:\Software\Octave-3.6.4\bin
TRILATERATOR_NOISY_2D_LEAST_SQUARES_OCTAVE_SCRIPT_PATH - Path to the
script that runs the non linear least squares numerical analysis.

TODO: Address some performance issues