Increase UM pes by a node

[blimlim]

Closes #28.

This PR increases the number of PEs allocated to the atmosphere by a node, bringing configuration in line with the recent change to the ESM1.5 configurations.

[MartinDix]

All good

[blimlim]

Logs from runs with 192 vs 240 pes show that the atmosphere waits more for the ocean in both cases, the opposite of what we saw for ESM1.5:

192 UM PEs:

Walltime Used: 01:20:31
Atmosphere logs:

   ROUTINE              CALLS  TOT CPU    AVERAGE   TOT WALL  AVERAGE  % CPU    % WALL    SPEED-UP
...
 5 GETO2A_COMM          2920    373.10      0.13    373.10      0.13    7.86    7.86      1.00

Ocean logs:

oasis_recv                          123.062082
oasis_send                            1.229582
oasis_recv1                          23.143442
oasis_send1                           0.795914

240 UM PEs:

Walltime Used: 01:20:07
Atmosphere logs

                              Non-Inclusive Timer Summary for PE    0
   ROUTINE              CALLS  TOT CPU    AVERAGE   TOT WALL  AVERAGE  % CPU    % WALL    SPEED-UP
  1 GETO2A_COMM          2920    954.95      0.33    954.95      0.33   20.22   20.22      1.00
2  ATM_STEP             ****    737.34      0.04    737.37      0.04   15.61   15.61      1.00

Ocean logs:

oasis_recv                          118.235277
oasis_send                            1.217324
oasis_recv1                          23.255084
oasis_send1                           0.781327

Increasing the UM PEs only appears to make the atmosphere wait more, with no effect on total walltime.

I'll try adding a node to the ocean.