Changes

• [Search directory] Append / instead of prepending ./ for quick cd (#185). This is a lot more natural, more comprehensible, takes up less space, more fish-y (same as what happens when you autocomplete a directory), and should lead to less bugs around search directory in the future.
• Set SHELL and FZF_DEFAULT_OPTS in wrapper around fzf (#194). Before FZF_DEFAULT_OPTS was set in config.fish. By moving that code into an internal wrapper, we no longer dirty the shell environment and eliminate the side effect of changing fzf when it is executed outside the plugin.
• Mention removing fzf_configure_bindings from config when uninstalling (e0b0cbb)