Change separator of commands in a pane.

[pjezusek]

Hi,

this merge request is related to the issue #133. For now teamocil joins commands in commands section with ';' symbol. The problem is that it does not work well with the terminal history. I think, in most cases only the last command is repeatable. The change gives users a possibility to choose between one liners:

[...]
- panes:
  - echo foo; echo bar
[...]

or commands performed one by one:

[...]
- panes:
  - commands:
    - echo foo
    - echo bar
[...]

PS.: Thank you for this cool gem.