Add a command line interface to the binary and remove parts
that were hardcoded.
new --help is:
```
pslink 0.1.0
Dietrich <dietrich@teilgedanken.de>
A simple webservice that allows registered users to create short links including qr-codes.
Anyone can visit the shortened links. This is an ideal setup for small busines or for publishing papers.
USAGE:
pslink [OPTIONS] [SUBCOMMAND]
FLAGS:
-h, --help Prints help information
-V, --version Prints version information
OPTIONS:
--db <database> The path of the sqlite database [env: PSLINK_DATABASE=] [default: links.db]
-i, --hostip <internal_ip> The host (ip) that will run the pslink service [env: PSLINK_IP=] [default:
localhost]
-p, --port <port> The port the pslink service will run on [env: PSLINK_PORT=] [default: 8080]
-t, --protocol <protocol> The protocol that is used in the qr-codes (http results in slightly smaller codes
in some cases) [env: PSLINK_PROTOCOL=] [default: http] [possible values: http,
https]
-u, --public-url <public_url> The host url or the page that will be part of the short urls. [env:
PSLINK_PUBLIC_URL=] [default: localhost:8080]
--secret <secret> The secret that is used to encrypt the password database keep this as inacessable
as possible. As commandlineparameters are visible to all users it is not wise to
use this as a commandline parameter but rather as an environment variable. [env:
PSLINK_SECRET=] [default: ]
SUBCOMMANDS:
runserver Run the server
create-admin Create an admin user.
generate-env Generate an .env file template using default settings and exit
migrate-database Apply any pending migrations and exit
help Prints this message or the help of the given subcommand(s)
```
