Build phalcon for php7, binaries unavailable :s (20160503):
$ sudo su
$ apt-get install build-essential git php-dev libpcre3-dev
$ cd /usr/src
$ git clone https://github.com/phalcon/zephir.git
$ git clone https://github.com/phalcon/cphalcon.git
$ ln -sf /usr/src/zephir/bin/zephir /usr/bin/zephir
$ export ZEPHIRDIR=/usr/src/zephir
$ cd cphalcon
$ git checkout php7-parsers
$ zephir build -backend=ZendEngine3
References:
https://github.com/phalcon/cphalcon/tree/php7-parsers
http://phalcon.io/phalconphp-and-php7