Fixes no-threads version

We weren't "releasing the hounds" for the non-pthread case.
Allows one thread in threaded mode

On Akaros, -t will put the process in MCP mode.  -t 1 will be one
thread, MCP mode, on a CG core (not core 0, no IRQs).  Without -t, it
will be in SCP mode, on core 0.
Makes Akaros's nsec() finer grained

We don't actually return the current unix time.  Instead, it's the
amount of nsec since boot.  This is fine for the usage of nsec().
Adds a gitignore