Upgrade from 1.8.1 to 1.10.1.

Please note: several vendor's modules:
o) http_geoip
o) http_image_filter
o) http_perl
o) http_xslt
o) mail
o) stream

as well as third-party modules, like:
o) brotli
o) dynamic_upstream
o) echo
o) eval
o) headers_more
o) http_redis
o) lua
o) njs
o) passenger
o) setmisc
o) small_light

have been reconfigured as dynamic modules.
Also, the spdy module has been removed from 1.10.x branch and replaced
by httpv2 module.

In case of using of any of those modules it's highly recommend to review
and update the nginx configuration file - nginx.conf.