unfreeze Shapeless (by fixing bad merge)

when I merged #206, apparently I messed it up

Author: SethTisue

common.conf

@@ -67,8 +67,7 @@ vars: {
   scalatest-ref                : "scalatest/scalatest.git#2.2.3-and-greater"
   // fixed sha/tag (a compromise), the sha points at master that supports Scala 2.11
   spire-ref                    : "non/spire.git#3d2a41e91a1f6946fac63660f6157d4a6e4a281d"
-  // https://github.com/scala/community-builds/issues/202
-  shapeless-ref                : "milessabin/shapeless.git#d6a4f56e0783655c48244ec23c4f4c2d98401a72"
+  shapeless-ref                : "milessabin/shapeless.git"
   scoverage-ref                : "scoverage/scalac-scoverage-plugin.git#1.0.2"
   sbt-ref                      : "adriaanm/sbt.git#community-build" // 0.13.7-M2 + drop ListBuffer.readOnly (after 0.13.7-M2, new dependencies were added --> TODO: add them here as well)