remove parse-repo dep

[stephenmathieson]

replace with something less shitty

it's leaky and only useful for this app, so we could just build it in

[stephenmathieson]

probably something like:

// get "bar" from "foo/bar@*"
const char *package_parse_name(const char *slug);
// get "foo" from "foo/bar@*"
const char *package_parse_owner(const char *slug);
// get "master" from "foo/bar@*"
const char *package_parse_version(const char *version);