Rename boards

[RyanRoberts]

Is your feature request related to a problem? Please describe.
Can't rename boards once created or no clear way to do it.

Describe the solution you'd like
Something like: $ tb -e MyTasks Todos could rename a MyTasks board to Todos…

[JordanAdams]

I almost feel like this could expand to updating task descriptions too. If that were the case, we could use of the @ syntax for distinguishing between board and task updates:

Rename a board
$ tb -e @cooking baking

Update a task
$ tb -e 1 Do something else

Ignore me. It looks like editing tasks is already a thing

[pavlochernovyy]

Made a PR.