Add `reload!` to `lotus console`

This patch adds a `reload!` method during `lotus console` sessions, much
like what is available during a `rails console` session. `reload!` will
simply call `Kernel.exec $0` to re-execute the running process after
outputting a message that it is doing so.

Signed-off-by: David Celis <me@davidcel.is>
ah right!