Fix build command to handle provider repos correctly
This fixes the following issues:

 * set correct distribution type (tar or zip)
   * e.g. when your local satis overrides that of the upstream (GitHub)
   * dist urls were ignored when previously no dist was 'provided' (e.g. with SVN)
 * set the correct dist reference

Resolves: #57

Thanks to @njam for reporting!
Remove &.
Merge pull request #58 from till/bugfix/dist-downloads-where-there-were-none-before

Bugfix for dists