$config_url should be composed from $rawRepo, not $basedir

`$config_url` needs to be composed of `$rawRepo + "/config"` and not `$basdir + "/config"`.

This yields the correct URL [https://raw.github.com/TechEmpower/FrameworkBenchmarks/master/config] instead of [C:\FrameworkBenchmarks/config].
Merge pull request #420 from kppullin/patch-6

Same as #419. I've not tested, but merging anyway.

$config_url should be composed from $rawRepo, not $basedir