LaneFooter not visible when there's no card in stack

[zxsure]

Describe the bug When provide customzied component for LaneFooter, and if stack is empty, footer it not show.

To Reproduce Steps to reproduce the behavior:

1. Create a customized component for LaneFooter.
2. Render while react-trello.

Expected behavior LaneFooter should show even if there's no card in stack

Screenshots If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context Source code seems checking if card length === 0, maybe just remove that check.

[TiagoAndreAlmeida]

i think this lib is not being maintened, which is sad. this is a great lib