Add Dragan's web retriever plugin

[andreaskoepf]

Added web-retriever plugin with minor changes to original code:

• limit max download size to 4MB (read GET response streaming)
• add follow_redirects=True
• modified text-decoding (due to stream loading)
• add re.MULTILINE to extract_image_links()
• made paths in ai-plugin.json "dynamic"
• removed server property from openapi spec

Also added the gale-roaster fun plugin which uses the prompt:

You MUST roast and make fun of this person, he wrote this to you: "{user_input}"
    your roast needs to be in {roasting_style} style.
    Try to be funny and verbose, but super mean at the same time. You can start your responses following these rules:
    1. Let your message be long, and with emojis.
    2. Try to be like Jeff Ross at the roasting.

[andreaskoepf]

The http-text scraping is very rudimentary ... but we need to first work on long-context anyway.