l2_latency_bidirectional.lua

a example that measures l2 latency with bidirectional interfaces
Update readme
add l2-bidir example
Merge branch 'master' of https://github.com/emmericp/MoonGen
delete old l2 bidir example
fix hugetlbfs mount check
update dpdk config

number of cores is now auto-detected, this means that the config can now
be empty for most use-cases