bufferjs/concat & bufferjs/add-chunk no longer exists.

The latest 2.0.0 bufferjs no longer has bufferjs/concat.js and bufferjs/add-chunk, which is apparently used by filternet. The 2.0.0 version changed this behavior, thus causing filternet to fail while loading. A quick solution is to force the bufferjs dependency to "=1.1.0" vs ">=1.0.0", which solves this problem.