Add NAS basic example

Author: kejacobson

examples/basic/nas.py

@@ -0,0 +1,7 @@
+from pbs4py import PBS
+
+group = 'a1234'  # replace your charge number here
+nas = PBS.nas(group, proc_type='bro', queue_name='devel', time=2)
+commands = [nas.create_mpi_command('nodet_mpi', 'debug')]
+nas.requested_number_of_nodes = 4
+nas.write_job_file('devel.pbs', 'debug', commands)