Make (memory) limits human readable

Right now, Isolation section shows everything as in MB, which is really hard to understand. Start to use the ByteSize type (from http://golang.org/doc/effective_go.html#constants) to make them more human readable.
The default limit is 16EB but I'm fine showing it as "unlimited" if you prefer that.

Question is, do you want to keep the current value (MaxInt64 - which is half of the default value aka 8EB) or want me to replace it with MaxUint64 (16EB)? Or maybe we should set some other upper limit cause EB (or PB) is still huge.