Set tmux layout after each pane creation

The tmux layout need to be set after each pane creation in order to prevent the lack of space and a "create pane failed: pane too small" error
Merge pull request #128 from doitian/remove-pry-in-file

Remove stray pry require.
Merge pull request #130 from doitian/allow-start-tumuxinator-in-tmux-session

Allow starting tmuxinator within a tmux session.
Revert indent
Merge pull request #131 from antoinelyset/patch-1

Set tmux layout after each pane creation.
[Fixes #126] Check for both pane-base-index and base-index.
Update readme with pre_window and fix typo.
Bump to 0.6.3.
Add gem version badge.
Move badges to a new line.
Specify directory explicitly when creating new window.

When run tmuxinator in tmux session, the default directory of new window
is overrided by the current tmux session default directory.