Merge pull request #116 from ypocat/master

support for set ex/px/nx/xx for redis 2.6.12 and up
libevent.a to encpasulate event abstractions like epoll, kequeue etc.
define __offsetof only if it is not defined
Update README.md
Replace MD5 implementation

Replace the MD5 code with an alternative implementation, better suited
to this codebase.
Replace the MD5 code with an alternative implementation, better suited to this codebase (paravoid).
Move nutcracker to sbin instead of bin

nutcracker is a daemon, so it obviously belongs to /usr/sbin, not
/usr/bin/.
Add a manpage

Add a nutcracker.8 manpage mostly based off nutcracker --help.
Merge pull request #125 from paravoid/manpage

Add a manpage
Merge pull request #124 from paravoid/move-to-sbin

Move nutcracker to sbin instead of bin
rename evflags to events
rename evbase to event_base; rename nc_event.h EV_ to EVENT_
trivial renames
kevent() should wait indefinitely when timeout < 0; also introduced conn_to_ctx helper func
introducing event_add_in() and event_del_in() for readable events
can't ASSERT(!conn->connecting) in rsp_recv_next() because a fresh connect() might fail with errno which triggers a readable event on server socket
checking NC_HAVE_BACKTRACE requires nc_core.h to be included first
use event_base in struct context
set descriptor to -1 after it is close() - helps debugging
reinstate EPOLLHUP