Adds basics for GROUP recording mode
Extends functionality of WeightMonitor

Implements more general load_patterns to accomodate for different
patterns in the pre and post population.
Fixes a bug in the GROUP implementation
Removes ISPS from EPSP example sim

This must have been the cause for confusion. This commit removes
GABA input from the postsynaptic neuron.
Updates Makefile for build/home
Merge branch 'master' of https://github.com/fzenke/auryn