TS-2187: use nonblock eventfd in EventNotify

1) Use nonblock eventfd, so that we can tolerate write() failed with
   errno EAGANIN – which is acceptable as the signal receiver will be
   notified eventually in this case.

2) After using nonblock eventfd, read() will not block in wait(). So
   I use epoll_wait() to implement block behavior, just like timedwait().

3) nonblock eventfd can fix a potential problem: if receiver didn't
   read() data immediately, senders might block in write().

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
TS-2187: Fix return in EventNotify::wait()

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
TS-2209 add support for lowercasing all substitutions in regex_remap
udpated release notes
TS-2217: remove the option to turn off body factory - setting it to 0
will result in empty responses
TS-2144 Avoid race on e.g. -Cclear which would crash the process
Added TS-2144.
Update docs for the header_rewrite plugin
comment on the units for TSContScheduleEvery()
TS-2187: 'nr' set but not used in EventNotify::signal()

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
TS-2201: split drainIncomingChannel two thread, one handle Broadcast message and other handle Reliable(TCP) request.
Fix typo in the hook used
TS-2232: log level should be change from Status to Debug