Problem: BigchainDB and Tendermint inconsistencies because disjoint services (#2242)

Solution
Since BigchainDB and Tendermint are so tightly coupled we need to introduce a process supervisor to make them act like a single microservice, so that if BigchainDB crashes, Tendermint does as well and both are restarted and Tendermint requests a connection towards the proxy app.

In Kubernetes, they can be exposed as part of a one POD.
For BigchainDB as a system service/process, we need to introduce a process supervisor such as systemd.
This PR only solves the former.

Changes
Upgrade deployment from Tendermint v0.12.0 to v0.19.0
Update some documentation
Fix nginx-http entrypoint issues.
Update generate-configs.sh script to handle config generation without https-certificates.
Update Dockerfile to process dependency links introduced by abci
Integrate BigchainDB and Tendermint as a single microservice.
This required making BigchainDB to be exposed as a statefulset.
Introduce new liveness probe checks.
Issues Resolved
Partially fixes #2232

k8s/nginx-https/nginx-https-dep.yaml

@@ -12,7 +12,7 @@ spec:
       terminationGracePeriodSeconds: 10
       containers:
       - name: nginx
-        image: bigchaindb/nginx_https:2.0.0-alpha
+        image: bigchaindb/nginx_https:2.0.0-alpha3
         imagePullPolicy: Always
         env:
         - name: NODE_FRONTEND_PORT
@@ -74,17 +74,12 @@ spec:
           valueFrom:
             configMapKeyRef:
               name: tendermint-config
-              key: tm-pub-key-access
-        - name: TM_BACKEND_HOST
-          valueFrom:
-            configMapKeyRef:
-              name: tendermint-config
-              key: ngx-tm-instance-name
+              key: bdb-pub-key-access
         - name: TM_P2P_PORT
           valueFrom:
             configMapKeyRef:
               name: tendermint-config
-              key: tm-p2p-port
+              key: bdb-p2p-port
         - name: AUTHORIZATION_MODE
           valueFrom:
             configMapKeyRef:
@@ -107,10 +102,10 @@ spec:
           name: ngx-port
         - containerPort: 9986
           protocol: TCP
-          name: tm-pub-key
+          name: bdb-pub-key
         - containerPort: 46656
           protocol: TCP
-          name: tm-p2p-port
+          name: bdb-p2p-port
         livenessProbe:
           httpGet:
             path: /health