[NEW] Install Magento on Ubuntu 18.04 (linode#1950)

* Reconcile Ubuntu 16.04 Magento installation guide with Ubuntu 18.04

* Improve readability.

* Initial copy edit.

* More copy edits

* add screenshots

rebuildtheme (linode#2018)

rebuildtheme (linode#2018)

Remove mixed whitespace (linode#1708)

Rebuild theme - Hugo 0.38.2 (linode#1685)

Rebuild theme (linode#1679)

Rebuild theme (linode#1676)

Rebuild theme (linode#1663)

Block storage graphics and locations update (linode#1646)

* added BS datacenters

* updated graphics in bs guide to show newer kernel

* new bs locations in add a volume dropdown

Rebuild theme (linode#1649)