Add PHP7 Extensions

To see a list of available extensions:

sudo apt-cache search php7

This generates a list of all available extensions for php7 available for installation.

Wordpress needs, Curl, GD, and Mcrypt, as well as php7-mysql.

sudo apt-get install php7.0-curl php7.0-gd php7.0-mcrypt php7.0-sqlite3 php7.0-bz2

Adding Sqlite3 and Bzip just because.