auto-build: only try to download sources packages if there are any

Rectifies previous error condition when attempting to download an empty
URL, which cURL evaluates as merely "http://".
sublime-text-installer: initial commit

Fedora users, rejoice! This RPM installs your favourite text editor to
/opt and, when I eventually get around to setting up a repository, will
keep it up to date for you. No more unversioned binaries hanging around
;-)