Refresh "Support Bitcoin" page

This pull request can be previewed live here:
http://bitcoinsupport.zapto.org/en/support-bitcoin

Add link to the "Getting started" page
Add dedicated text about the importance of running full nodes
Add dedicated text about mining
Promote decentralized mining (smaller pools, P2Pool, getworktemplate)
Promote all Bitcoin non-profit organizations
Invite people to help merchant directories