jupyterhub resource report

resource_report.py

```
global config:
https://github.com/pangeo-data/pangeo-cloud-federation/blob/eef3a575973f9789bcdb496b794e2334a88b4661/deployments/nasa/config/common.yaml#L59-L64
Here is a handy function to print some user-friendly information. But this is for the node(EC2) that the pod is on, rather than the resource limits identified in the JupyterHub config above. So in our case, the effective resources available to you are about 1/2 of the total since we have set resource limits with the intension of putting two user pods on every machine...

def tell_system_status():
        # from https://www.programcreek.com/python/example/53878/psutil.disk_usage
        import psutil
        import platform
        import datetime

        os, name, version, _, _, _ = platform.uname()
        version = version.split('-')[0]
        cores = psutil.cpu_count()
        cpu_percent = psutil.cpu_percent()
        ram = psutil.virtual_memory().total >> 30
        memory_percent = psutil.virtual_memory()[2]
        disk_percent = psutil.disk_usage('/')[3]
        boot_time = datetime.datetime.fromtimestamp(psutil.boot_time())
        running_since = boot_time.strftime("%A %d. %B %Y")
        response = "I am currently running on %s version %s.  \n" % (os, version)
        response += "This system is named %s \n" % (name)
        response += "It has %s CPU cores.  \n" % (cores)
        response += "It has %s Gigabytes of RAM.  \n" % (ram)
        response += "Current disk_percent is %s percent.  \n" % disk_percent
        response += "Current CPU utilization is %s percent.  \n" % cpu_percent
        response += "Current memory utilization is %s percent. \n" % memory_percent
        response += "it's running since %s. \n" % running_since
        return response 
    
print(tell_system_status())

```