[pdal] filters.attributes reference failing and libpcl missing when using docker build v1.4

[Howard Butler]

A follow up to let you know that the image is now refreshed and should behave as expected. Please let me know if you still have any issues.

> [hobu at pyro docker (master)]$ docker run pdal/pdal:1.4 pdal --drivers
> 
> ============================ ===================================================
> Name                         Description
> ============================ ===================================================
> filters.approximatecoplanar  ApproximateCoplanar Filter
> filters.attribute            Assign values for a dimension using a specified
>                              value, an OGR-readable data source, or an OGR SQL
>                              query.