Use https download link
MODIFY
freebsd-10.3-amd64.json
freebsd-10.3-amd64.json
"iso_name": "FreeBSD-10.3-RELEASE-amd64-disc1.iso",
"memory": "1024",
"metadata": "floppy/dummy_metadata.json",
- "mirror": "http://ftp.freebsd.org/pub/FreeBSD",
+ "mirror": "https://download.freebsd.org/ftp",
"mirror_directory": "releases/amd64/amd64/ISO-IMAGES/10.3",
"name": "freebsd-10.3",
"no_proxy": "{{env `no_proxy`}}",

MODIFY
freebsd-10.3-i386.json
freebsd-10.3-i386.json
"iso_name": "FreeBSD-10.3-RELEASE-i386-disc1.iso",
"memory": "1024",
"metadata": "floppy/dummy_metadata.json",
- "mirror": "http://ftp.freebsd.org/pub/FreeBSD",
+ "mirror": "https://download.freebsd.org/ftp",
"mirror_directory": "releases/i386/i386/ISO-IMAGES/10.3",
"name": "freebsd-10.3-i386",
"no_proxy": "{{env `no_proxy`}}",

MODIFY
freebsd-11.1-amd64.json
freebsd-11.1-amd64.json
"iso_name": "FreeBSD-11.1-RELEASE-amd64-disc1.iso",
"memory": "1024",
"metadata": "floppy/dummy_metadata.json",
- "mirror": "http://ftp.freebsd.org/pub/FreeBSD",
+ "mirror": "https://download.freebsd.org/ftp",
"mirror_directory": "releases/amd64/amd64/ISO-IMAGES/11.1",
"no_proxy": "{{env `no_proxy`}}",
"template": "freebsd-11.1-amd64",

Use https download link

Signed-off-by: Li-Wen Hsu <lwhsu@lwhsu.org>