Use band-specific no data values of source image during ingest and build pyramid

[djohnson729]

From a review of the ingest code, if the user does not specify a no data override value on the command line, we use the no data value of band 0 for all of the bands. We should consider changing this to use the actual no data value for each individual band separately.

Similarly, when building the pyramid, we use the no data value for band 0 as the no data value for all of the bands. We should consider using the no data value for each individual band.

[djohnson729]

@wncampbell suggested modifying the ingest command to allow nodata values for each band to be specified. The user should be allow to specify a single value or multiple arguments for the nodata option. For example "-nd -9999" would override the nodata value for all bands of the source image to -9999, where "-nd nan -9999 nan" would use NaN for bands 0 and 2 and -9999 for band 1.