Add new vegetation indexes to the algorithm

[HectorJBastidasG]

Add new vegetation indexes to the algorithm(Ej. OSAVI, LAI, etc) to https://github.com/RentadroneCL/Precision_Agriculture/blob/master/veg_index.py, which can be calculated from the 5 spectral bands described in https://github.com/RentadroneCL/Precision_Agriculture#multispectral-bands