Configuration tools

See #15003

"Check config" example, using the config file created by run-tests.sh:

$ ./tmp/GOPATH/bin/arvados-server config-check < ./tmp/arvados.yml  
deprecated or unknown config entry: Clusters.zzzzz.HTTPRequestTimeout
deprecated or unknown config entry: Clusters.zzzzz.NodeProfiles
Your configuration is relying on deprecated entries. Suggest making the following changes.
--- without-deprecated-configs
+++ relying-on-deprecated-configs
@@ -92,7 +92,8 @@
     Services:
       Controller:
         ExternalURL: "" 
-        InternalURLs: {}
+        InternalURLs:
+          http://localhost:42003: {}
       DispatchCloud:
         ExternalURL: "" 
         InternalURLs: {}
@@ -113,7 +114,8 @@
         InternalURLs: null
       RailsAPI:
         ExternalURL: "" 
-        InternalURLs: {}
+        InternalURLs:
+          https://localhost:39269: {}
       WebDAV:
         ExternalURL: "" 
         InternalURLs: {}
exit status 1

"Dump config" example, using the config file created by run-tests.sh:

$ ./tmp/GOPATH/bin/arvados-server config-dump < ./tmp/arvados.yml
WARN[2019-04-26T14:36:32.094970598-04:00] deprecated or unknown config entry: Clusters.zzzzz.HTTPRequestTimeout
WARN[2019-04-26T14:36:32.095022801-04:00] deprecated or unknown config entry: Clusters.zzzzz.NodeProfiles
Clusters:
  zzzzz:
    API:
      MaxItemsPerResponse: 1000
      MaxRequestAmplification: 4
    CloudVMs:
      BootProbeCommand: "" 
      Driver: "" 
      DriverParameters: null
      ImageID: "" 
      MaxCloudOpsPerSecond: 0
      SSHPort: "" 
      SyncInterval: 0
      TimeoutBooting: 0
      TimeoutIdle: 0
      TimeoutProbe: 0
      TimeoutShutdown: 0
    Dispatch:
      MaxProbesPerSecond: 0
      PollInterval: 0
[...]