Add '--nostream' to pdal pipeline

Streaming mode is default for 1.8.0 but also requires the '--bounds' parameter.  Until this can be incorporated use the old standard mode (which moves all points into memory) through '--nostream'.

opendm/dem/pdal.py

@@ -155,6 +155,7 @@ def run_pipeline(json, verbose=False):
     cmd = [
         'pdal',
         'pipeline',
+        '--nostream',
         '-i %s' % jsonfile
     ]
     if verbose: