Merge pull request #28 from telefonicaid/bug/subscribe_context_errors

Bug fixes regarding ngsi10 subscriptions
Merge branch 'develop' into feature/subscribe_context_json
fixed entityId for XML - 'id' as field, 'isPattern' and 'type' as attributes
Merge pull request #30 from telefonicaid/feature/subscribe_context_json

Feature/subscribe context json
Merge branch 'develop' into feature/notify_context_json