Bug 969090 - Make b2g-ps read process/thread name from /proc/<pid>/status.

This is helpful on the ICS emulator, which uses an old kernel version
where /proc/<pid>/comm doesn't exist.
Merge pull request #151 from jld/bug969090-b2g-ps-status-name

Bug 969090 - Make b2g-ps read process/thread name from /proc/<pid>/status. r=dhylands