Simplify installation using a script

[Alphix]

Here's a bunch of patches which simplify the installation by providing an installation script.

Also, some bugfixes (2 first patches, should be applied whether you agree with the rest of the PR or not)

Added features:

• short hostnames (turris) will be redirected to the FQDN (turris.example.com)
• acme.sh is used via the webroot functionality instead of standalone (which means no messing with default turris files or disabling port 80)
• connections on port 80 (except letsencrypt) will be redirected to https
• no messing with the files below /root
• self-contained installation directory
• acme.sh is provided by a git submodule
• uninstallation script