Migrate to TF2

[perezsolerj]

TF package was marked as deprecated in hydro version. We should move the ROStoWorldTF publisher to TF2, as it is more efficient:

http://wiki.ros.org/tf2/Migration

[davidfornas]

From that thread:

As tf2 is a major change the tf API has been maintained in its current form. Since tf2 has a superset of the tf features with a subset of the dependencies the tf implementation has been removed and replaced with calls to tf2 under the hood. This will mean that all users will be compatible with tf2. It is recommended for new work to use tf2 directly as it has a cleaner interface. However tf will continue to be supported for through at least J Turtle.

So, if understand it correctly we are already silently using TF2 through TF at least until ROS K, so we have plenty of time if we want to change it for clarity but the code is already more efficient.