### Please describe the problem.

When creating a Camera repository on android, the .thumbnails/ directory (containing useless crushed JPGs and even more useless oodles of thumbnail metadata databases) is annexed. This leads to confusion (assistant tries to annex database and thumbnails in modification) and waste (uploading/annexing unusable/unneeded metadata).

### What steps will reproduce the problem?

Install git-annex on Android and choose the defaults for a camera repository.


### What version of git-annex are you using? On what operating system?

4.20130601, Android 4.2.2


### Please provide any additional information below.

[[!format sh """
# If you can, paste a complete transcript of the problem occurring here.
# If the problem is with the git-annex assistant, paste in .git/annex/daemon.log


# End of transcript or log.
"""]]

> I've [[done]] this, however the .gitignore file it writes will
> not actually be used by the assistant until it gets support
> for querying gitignore settings from git. There is already a
> bug tracking that, and it's in process. --[[Joey]] 
