new file: .gitignore

Problem
-------
```
[Thu 14/02/27 09:13 GMT][pts/0][amd64/freebsd10.0/10.0-STABLE][5.0.5]
<paj@beaujolais:~/dotfiles>
zsh 835  (git)-[master]-% git --version
git version 1.8.5.2
[Thu 14/02/27 09:14 GMT][pts/0][amd64/freebsd10.0/10.0-STABLE][5.0.5]
<paj@beaujolais:~/dotfiles>
zsh 836  (git)-[master]-% git status
On branch master
Your branch is up-to-date with 'origin/master'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)
  (commit or discard the untracked or modified content in submodules)

    modified:   .vim/bundle/OmniCppComplete (untracked content)
    modified:   .vim/bundle/SingleCompile (untracked content)
    modified:   .vim/bundle/TailMinusF (untracked content)
    modified:   .vim/bundle/dbext.vim (untracked content)
    modified:   .vim/bundle/golden-ratio (untracked content)
    modified:   .vim/bundle/snipmate.vim (untracked content)
    modified:   .vim/bundle/taglist.vim (untracked content)
    modified:   .vim/bundle/vim-makeshift (untracked content)
    modified:   .vim/bundle/vim-pipe (untracked content)
    modified:   .vim/bundle/vim-tut (untracked content)

no changes added to commit (use "git add" and/or "git commit -a")
[Thu 14/02/27 09:14 GMT][pts/0][amd64/freebsd10.0/10.0-STABLE][5.0.5]
<paj@beaujolais:~/dotfiles>
zsh 837  (git)-[master]-% cd .vim/bundle/vim-makeshift
[Thu 14/02/27 09:14 GMT][pts/0][amd64/freebsd10.0/10.0-STABLE][5.0.5]
<paj@beaujolais:~/dotfiles/.vim/bundle/vim-makeshift>
zsh 838  (git)-[master]-% git status
On branch master
Your branch is up-to-date with 'origin/master'.

Untracked files:
  (use "git add <file>..." to include in what will be committed)

    doc/tags

nothing added to commit but untracked files present (use "git add" to track)
```

Solution
--------

-   Add `.gitignore`