Alias to-master and add rename-branch to Git

- `git rename-branch` checks out master, moves the branch to a new
  name, and then checks out the new branch, enabling one to rename
  a branch "in line"
- `git ship` is an alias for `git to-master` that's a little easier
  to type.
Establish the Mail directory with Mutt.
Ignore binstubs everywhere.
Install Mutt and Procmail in bootstrap