removed unused .gitignore files

[mkhansenbot]

Fixes issue #56
Removes unused .gitignore files

[mjeronimo]

These were just placeholders to demonstrate the directory hierarchy. I'd rather keep them until the directories are populated, at which point they can be deleted.

[mkhansenbot]

We aren't going to need these gitignore files since we have one at the top level. I don't think we should have empty directories. Removing them will remove confusion for users coming to our repo. If they have to sift through a bunch of empty directories that will confuse them and waste their time. The overall heirarchy is being maintained here, just not empty files / directories. All the top level folders are still there.

[mjeronimo]

No, we aren't going to need these as .gitignore files. They are just there so that a file is present (and hence the directory shows up in the hiearchy). If you like, we can use a different filename, such as .TODO or something. The files are present to encourange the correct directory structure as the hiearchy is filled out. Let's discuss, if necessary.

[mkhansenbot]

Take a look at my branch here: https://github.com/mkhansen-intel/navigation2/tree/rm_gitignore/src

You'll see that all the main folders are still there (navigation, planning, etc.) We're just pruning the unpopulated leaf folders. There is still a clear hierarchy in place. Also, when people submit PRs for code review, we can ensure they put new code in the right place then. So I don't see a need for these placeholders anymore. They have served their purpose in my opinion, and they confuse new users.

[mjeronimo]

Yeah, I understand but disagree. The basic difference is: do we have a template that we fill out, or build incrementally. I prefer the former as it demonstrates the directories and files that will be populated. I believe that it limits confusion as well as the various message and test directories are already defined according to a uniform naming convention.

[mkhansenbot]

OK, just to document our stand-up discussion this morning, we agreed that we'll delete these files but add an outline of the directory structure we want to the contributing section of the documentation README file. Mike's going to make that change and push it to the branch as part of this PR.

[mjeronimo]

The outline of the directory structure won't be needed not that we're going to reorganize according the Steve's PR, so I went ahead and integrated this and will close this issue.