Milestone 3 reached

Milestone 3 is reached and with it Husk has aquired a set of new features:

• Online sources (keyservers, WKD, DANE) are now queried for missing certificates.
• Introducers are now available: certificates are only used if they are certified by an introducer and match its list of configured domains.
• Locals are available: These are certificates hand picked and added by the administrator.

Under the hood many improvements where added, mainly:

• A capable CLI dispatcher is added, so that there are now Husk native CLI commands to manage introducers and locals. See the documentation.
• The configuration of the logfile is now part of the main configuration file.
• A test framework was added to allow for end-to-end tests of Husk.