Update to ROS Indigo. This includes bugfixes as well as the ability to read bags that are compressed using the new LZ4 compression option.

• Add ability to 1) filter messages by time and 2) access bag start/stop time.
• New class, ros.TFTree, for working with stored TF messages
• Autocomplete paths to bags using ros.Bag.load()
• Update build to use Hydro
• Bugfixes for bags with bad definitions (#6)