v0.6.2: replace gnutls-openssl with nettle
* require nettle-dev instead of gnutls-openssl because gnutls-openssl is no longer supported on ArchLinux * upgrade fweelin version to 0.6.2
* require nettle-dev instead of gnutls-openssl because gnutls-openssl is no longer supported on ArchLinux * upgrade fweelin version to 0.6.2