chore(fixes): Unwrap yaml before converting and fix volume name variable

2 fixes:

- the first problem to resolve is that some volume names can have "-" in
the name. We now replace them by "_"
- the second problem is that k8s.io library truncates the lines and so
we cannot split the files by lines. We now "unwrap" the result.

TODO: globalize the `yaml.Marshal()` code to our own specific function

generator/configMap.go

@@ -232,5 +232,9 @@ func (c *ConfigMap) SetData(data map[string]string) {
 
 // Yaml returns the yaml representation of the configmap
 func (c *ConfigMap) Yaml() ([]byte, error) {
-	return yaml.Marshal(c)
+	if o, err := yaml.Marshal(c); err != nil {
+		return nil, err
+	} else {
+		return UnWrapTPL(o), nil
+	}
 }