Implement 'auxiliary' nodes of move_base in Android

[jubeira]

The navigation stack also uses some nodes which are smaller than move_base; some of them are required, others are optional.

Required:

• [x] TF extrinsics publisher
• [x] Map Server
• [x] Base Controller

Desirable:

• [ ] Velocity multiplexer
• [ ] Velocity smoother
• [ ] Safety controller

Optional:

• [ ] Diagnostic aggregator (monitoring)
• [ ] Joint state publisher (probably not required, research pending)

Not required:

• Robot state publisher (transformations between frames taken from robot description). This one is required by the RVIZ, so it can be considered as part of the Linux visualizer.

[adamantivm]

Note that some of these may be better to use a pure-rosjava equivalent or to implement such functionality in Java from scratch. For example, map_server I think is a python script, which won't run on Android, but what it does is very straightforward: read a PGM file and publish it to a given latched topic.

[jubeira]

@adamantivm good observation, I changed the title to reflect that possibility.

[jubeira]

Update: #63 adds tf publisher for extrinsics.

[jubeira]

Update: #64 adds a simple map server