Nextcloud update php5.6 to php7.0

Add these two lines to your /etc/apt/sources.list file
deb http://packages.dotdeb.org jessie all
deb-src http://packages.dotdeb.org jessie all

Key installation
wget http://www.dotdeb.org/dotdeb.gpg
cat dotdeb.gpg | apt-key add -

Update
apt-get update

Install PHP7
apt-get install libapache2-mod-php7.0 php7.0-apcu php7.0-apcu-bc php7.0-cli php7.0-common php7.0-curl php7.0-gd php7.0-igbinary php7.0-imagick php7.0-imap php7.0-intl php7.0-json php7.0-mbstring php7.0-mcrypt php7.0-mysql php7.0-opcache php7.0-phpdbg php7.0-readline php7.0-redis php7.0-sqlite3 php7.0-xml php7.0-zip

disable php5 enable php7
a2dismod php5
a2enmod php7.0
service apache2 restart

Modify the default php settings in php.ini for better performance:
opcache.enable=1
opcache.enable_cli=1
opcache.interned_strings_buffer=8
opcache.max_accelerated_files=10000
opcache.memory_consumption=128
opcache.save_comments=1
opcache.revalidate_freq=1