devel/pylint location fix

[Phil Pennock]

[ ports@ listed as current MAINTAINER ]

Port devel/pylint doesn't seem to be well distributed on the
ftp.CC.freebsd.org mirrors and can't be retrieved from the currently
defined master; ftp://ftp.logilab.org/pub/pylint/pylint-0.13.1.tar.gz
results in an FTP error after anonymous authentication:
  421 Service not available, remote server has closed connection.

Change the protocol to http: but leave the host and local path alone and
the file is retrievable, passing checksum tests..  Given that http is
generally lighter weight, should MASTER_SITES include the http: variant
before the ftp one?

Regards,
-Phil