bwi_common: 0.2.1-0 in 'hydro/distribution.yaml' [bloom]

Increasing version of package(s) in repository `bwi_common` to `0.2.1-0`:

- distro file: `hydro/distribution.yaml`
- bloom version: `0.5.4`
- previous version for package: `0.2.0-0`

## bwi_common

```
* Move ``bwi_planning_common`` here from the ``bwi_planning``
  repository (bwi_planning#1 <https://github.com/utexas-bwi/bwi_planning/issues/1>).
```

## bwi_gazebo_entities

- No changes

## bwi_mapper

- No changes

## bwi_planning_common

```
* Initial release to Hydro.
* Add roslaunch file checks.  This required providing default values
  for the ``map_file`` arguments.
* Install launch files.
* Move ``bwi_planning_common`` to ``bwi_common`` from the
  ``bwi_planning`` repository (bwi_planning#1 <https://github.com/utexas-bwi/bwi_planning/issues/1>).
* Updating bwi_planning code for the ICAPS 2014 paper.
* Added resolveDoor function.  Added ability to add cost samples using
  a service in the node.
* Added planning common (formerly segbot_common).
```

## bwi_tools

- No changes

## bwi_web

- No changes

## utexas_gdc

```
* Updated map PGM file to be obstacle free.
```