[incubator/couchdb] Increase default passwd length (#5661)

* [incubator/couchdb] Increase default passwd length

By default, `couchdb` will generate a secrets for a default
username/password. Previously, the default length for those was 10
chars. Bump the default password length to 20 as there's no real cost,
and it provides slightly more security.

I tested with `kubectl get secrets RELEASE_NAME -o json | jq
.data.adminPassword | sed 's/"//g' | base64 --decode` to verify the
password was previously 10 chars, and is now 20 charts.

* Update Chart.yaml

incubator/couchdb/Chart.yaml

@@ -1,5 +1,5 @@
 name: couchdb
-version: 0.1.5
+version: 0.1.6
 appVersion: 2.1.1
 description: A database featuring seamless multi-master sync, that scales from
   big data to mobile, with an intuitive HTTP/JSON API and designed for

incubator/couchdb/templates/_helpers.tpl

@@ -31,6 +31,6 @@ Create a random string if the supplied key does not exist
 {{- if . -}}
 {{- . | b64enc | quote -}}
 {{- else -}}
-{{- randAlphaNum 10 | b64enc | quote -}}
+{{- randAlphaNum 20 | b64enc | quote -}}
 {{- end -}}
 {{- end -}}