Make rosnode info show topic types of unconnected subscribers

[Sanoronas]

When running a node which has unconnected Subscribers rosnode info is unable to infer topic type.
In contrast rostopic info is able to resolve this.

• change rosnode info to use master.getTopicTypes() instead of master.getPublishedTopics('/')
• rename pub_topics variable to topic_types to match new content

[peci1]

LGTM, I've tested this locally.

Theoretically, this might introduce much higher traffic on systems with many topics, but I guess it's not a big problem because rosnode info is more a diagnostic tool than something that should be used as a part of a final system.