Subsonic support

Added

• Subsonic server support - this is dedicated to my Debian package maintainer
  Jerome Charaoui
• You can now specify which configuration file to use by using the --config
  flag.
• Added support for turning off TLS certificate check (--insecure_tls flag).
• Now check for server's support for HTTP range request, which can be turned off
  using the --no-range-check flag.

Changed

• Wrapped all calloc() calls with error handling functions.
• Various code refactoring

Fixed

• Remove the erroneous error messages when the user supplies wrong command line
  options.
• The same cache folder is used, irrespective whether the server root URL ends
  with '/'
• FreeBSD support

What's Changed

• Id3 by @fangfufu in #47
• Add freebsd support by @fangfufu in #48

Full Changelog: 1.1.9...1.2.0