Add address and directory command line options

Usage of lsweb:
  -addr=":8080": The address to bind on (eg. localhost:8080)
  -dir="$PWD": The directory to serve
Add a -dotfiles flag

Allows us to turn on or off dotfile listing:
 -dotfiles=false: Whether we should list dotfiles
Add three command line flags

Usage of lsweb:
  -addr=":8080": The address to bind on (eg. localhost:8080)
  -dir=".": The directory to serve
  -dotfiles=false: Whether we should list dotfiles

Merge branch 'feature/flags' into develop