Change the source URL to https URL, as http causes redirect error

Current http URL causes the following exception to be thrown:
Errno::ECONNREFUSED: Connection refused - connect(2) for "foobar.com" port 443
from /Users/xxx/.rbenv/versions/2.1.1/lib/ruby/2.1.0/net/http.rb:879:in `initialize'
from /Users/xxx/.rbenv/versions/2.1.1/lib/ruby/2.1.0/net/http.rb:879:in `open'