Fixes https://github.com/turt2live/matrix-media-repo/issues/239
Fixes https://github.com/turt2live/matrix-media-repo/issues/253

In various places in the code base, the address and port are joined using a `:`.
This causes issues with IPv6-addresses (see #247).
Address this by using net.JoinHostPort everywhere.

Signed-off-by: Silke Hofstra <silke@slxh.eu>

Fixes https://github.com/turt2live/matrix-media-repo/issues/188

This should help memory some more. See https://github.com/turt2live/matrix-media-repo/issues/237

Theory is that by dumping the streams we'll relieve any bytes held on by the S3 libraries. 

Includes early implementation of an embedded node, but not enabled because it breaks the whole compile chain.

They can realistically be anything, so we should just work with them. IPFS media IDs also wouldn't be sent through this very well.

Step towards https://github.com/turt2live/matrix-media-repo/issues/115

Fixes https://github.com/turt2live/matrix-media-repo/issues/84

We'd return a 500 when the token isn't found on the homeserver, but we should be returned a proper auth error. This just fixes the logic around the area to make that actually work.

Fixes https://github.com/turt2live/matrix-media-repo/issues/63

Fixes https://github.com/turt2live/matrix-media-repo/issues/205

Part of https://github.com/turt2live/matrix-media-repo/issues/209

Part of https://github.com/turt2live/matrix-media-repo/issues/209

Part of https://github.com/turt2live/matrix-media-repo/issues/209

Fixes https://github.com/turt2live/matrix-media-repo/issues/211

Fixes https://github.com/turt2live/matrix-media-repo/issues/206

Fixes https://github.com/turt2live/matrix-media-repo/issues/208

Fixes https://github.com/turt2live/matrix-media-repo/issues/207

Fixes #202