Tmux: fix new window path issue with Tmux v1.9

'default_path' is removed in tmux v1.9. This change does not create new
window/pane with the $PWD of active window.

This patch will re-enable the old functionality by adding
-c "#{pane_current_path}" to the commands for new windows and hor and
ver window splitting.

Tested-by: Ratheesh S <ratheeshreddy@gmail.com>
Signed-off-by: Ratheesh S <ratheeshreddy@gmail.com>