dvp build should format schema validation failures in a better way

[fdrozdowski]

Currently schema validation failures are printed as below -

BUILD FAILED.
(tools) bash-3.2$ dvp build -c ~/python-staged/plugin_config.yml 
Error: 'nameField' is a required property on ['repositoryDefinition']
{
  "identityFields": [
    "name"
  ], 
  "type": "object", 
  "properties": {
    "name": {
      "type": "string"
    }
  }
}
Validation failed on /Users/ravimukkamala/python-staged/schema.json. 
0 Warning(s). 1 Error(s) 

BUILD FAILED.

(tools) bash-3.2$ dvp build -c ~/python-staged/plugin_config.yml 
Error: 'PYTHON271' is not one of ['PYTHON27'] on ['language']
"PYTHON271"
Validation failed on /Users/ravimukkamala/python-staged/plugin_config.yml. 
0 Warning(s). 1 Error(s) 

BUILD FAILED.

In the above examples, instance on which validation failed (for e.g line starting with "PYTHON271") should only be printed if its a json blob like in example 1 above. If not, output looks little redundant.

┆Issue is synchronized with this Jira Bug by Unito