Implement /api/v1/stats

[snowch]

GET /api/v1/stats/ HTTP/1.1
Host: 127.0.0.1:8080
Accept-Encoding: gzip, deflate
REMOTE_ADDR: 86.138.132.112
Accept: */*
User-Agent: python-requests/2.6.0 CPython/2.7.5 Linux/3.10.0-1127.13.1.el7.x86_64
Connection: keep-alive
X-BDS-SESSION: /api/v2/session/5a1cec10-f62e-44dc-9692-e3f52a2dcc7c
Authorization: /api/v2/session/5a1cec10-f62e-44dc-9692-e3f52a2dcc7c

HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Length: 886
Content-Type: application/json
Date: Tue, 21 Jul 2020 14:11:29 GMT
Server: HPE Ezmeral Container Platform 5.1

{"result":"Success","objects":{"num_workers_by_purpose":[{"purpose":"primary","total":1,"installed":1},{"purpose":"proxy","total":1,"installed":1},{"purpose":"k8s","total":3,"configured":2,"ready":1}],"num_tenants":3,"num_all_tenants_by_tenant_type":[{"tenant_type":"site_admin","num_tenants":1},{"tenant_type":"k8s_admin","num_tenants":1},{"tenant_type":"docker","num_tenants":1},{"tenant_type":"k8s","num_tenants":0}],"num_k8s_clusters":1,"num_users":3,"num_sessions":151,"num_compute_nodes":1,"num_proxy_nodes":1,"num_active_jobs":0,"num_filesystems":1,"num_active_clusters":0,"num_active_clusters_current_user":0,"num_active_clusters_by_category":[],"num_stopped_clusters":0,"num_stopped_clusters_current_user":0,"num_stopped_clusters_by_category":[],"num_all_vnodes":0,"num_all_vnodes_by_tenant_type":[{"tenant_type":"docker","num_vnodes":0},{"tenant_type":"k8s","num_vnodes":0}]}}