Remove user.name from ~/.gitconfig

Since we have moved to the new format of including user-specific
information in a `~/.gitconfig.local` file, including the name in this
section is unnecessary.

This has the added benefit of making this plugin work out-of-the-box for
any user, provided they have their own `~/.gitconfig.local` file.
Add remote copy/paste support via Clipper

Clipper is a helpful utility for Mac which runs as a server for
receiving copy/paste clipboard buffers from remote machines.

This change adds support to `tmux` for sending the remote clipboard to
the local machine I'm running my terminal from. This saves me time when
wanting to copy/paste text from the remote session.

See https://wincent.com/products/clipper for more information.