Miscellaneous docker QoL improvements

[leogao2]

From @StellaAthena:

1. Store the hostfile in /job/hostfile so that the code automatically finds it and we don't need to provide it as an argument.
2. Install DeeperSpeed instead of DeepSpeed
3. The script lands you in ~/app/, which contains the contents of the GPT-NeoX repository. Would it be possible to have the GPT-NeoX repo be one layer deeper, so that it drops you in ~/app/ which contains the directory gpt-neox? That would be very pleasant but isn't necessary.

Addresses 1 & 2, fixes XY behind 3

[StellaAthena]

This creates a job directory and puts the host file in it, but the directory is not in app! I believe this is fixed by changing line 10 to kubectl cp $PWD/hostfile $MASTER_ID:/app/job.

[leogao2]

I double checked with deepspeed documentation, /job/hostfile is the correct path.