Suggestions for prepSentinel() improvements

[aTnT]

See issue#10, copied below for convenience:

Maybe some improvements to add to prepSentinel() are:

• add somehow the names of the bands to the output .tif files. The L2A outputs are available with the names below in the original .SAFE data, but with prepSentinel() the band names get lost:

band.order <- list("aux" = c("AOT", "CLD", "SCL", "TCI", "WVP", "SNW"), "refl" = c("B01", "B02", "B03", "B04", "B05", "B06", "B07", "B08", "B8A", "B09", "B10", "B11", "B12"))

• add a function input variable SAFE = true to avoid step 4 above (create a .zip file)