Use tmux capture-pane -p if available
Extract tmuxcomplete#init, reuse default s:capture_args
Update version to 0.0.4
Merge pull request #35 from wellle/justinmk-tmux1.6

#34 Support for tmux 1.6
Fix g:tmuxcomplete#capture_args
Merge pull request #36 from junegunn/master

Fix g:tmuxcomplete#capture_args
tmux 1.6: fix capture-pane test

- without [[...]], error message clobbers stdout.