lock free mempool implementation

Lock free algorithm based on: Maged M. Michael & Michael L. Scott's
Correction of a Memory Managment Method for Lock-Free Data Structures
of John D. Valois's Lock-Free Data Structures. Ph.D. dissertation

Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com>
Merge branch 'master' of github.com:accelio/accelio