Adding bps unit type for network gear

Currently there is no way to accurately plot network bps statistics, as network 'bits' are an SI unit type (steps of 1000), versus storage 'bits' which are binary based (steps of 1024).  This change adds a 'bps' unit type to the axis labels, which is nearly identical to bits but uses 1000 to calculate the units instead of 1024 (along with different exts).  This is my first ever pull request so be gentle :)