### Please describe the problem.

annex add  seems to ignore content under directories having . prefix.

We thought to unify (across direct/indirect/v6) adding files to annex repository by using 'git annex add' with corresponding setting for largefiles for any addition, but it seems to ignore content under .-prefixed directories, unlike git

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

6.20161122+gitg9f179ae-1~ndall+1

### Please provide any additional information below.

[[!format sh """
hopa:/tmp/datalad_temp_test_annex_add_no_dotfilesqMXck8
$> git status                      
On branch master
 
Initial commit

nothing to commit (create/copy files and use "git add" to track)

$> mkdir .dir dir; echo 123 > .dir/123; echo 124 > dir/124

$> git status
On branch master

Initial commit

Untracked files:
  (use "git add <file>..." to include in what will be committed)

	.dir/
	dir/

nothing added to commit but untracked files present (use "git add" to track)

$> git annex add -c 'annex.largefiles=nothing' .
add dir/124 (non-large file; adding content to git repository) ok
(recording state in git...)

$> git status
On branch master

Initial commit

Changes to be committed:
  (use "git rm --cached <file>..." to unstage)

	new file:   dir/124

Untracked files:
  (use "git add <file>..." to include in what will be committed)

	.dir/


# and with regular git
$> git  -c 'annex.largefiles=nothing' add . 

$> git status
On branch master

Initial commit

Changes to be committed:
  (use "git rm --cached <file>..." to unstage)

	new file:   .dir/123
	new file:   dir/124


"""]]

Ref: https://github.com/datalad/datalad/issues/1027

[[!meta author=yoh]]

[[done]]; oh -- it is RTFM: --include-dotfiles  --[[yoh]]