Added Blockchain Bootstraping Tutorial

Per @laanwj request in #3724

Fixing Checkpoints Comment

Fixed Image Paths

Removed requirement.

Update Torrent Links.

Update Links 2

Link would not work.

2 Small Fixes

Changed in to from

@laanwj suggestion on safety
refactored bootstrap info for doge infra and screenshots
Merge pull request #539 from patricklodder/1.7.2-dev-merge-btc-bootstrap-info

0.9.2 bootstrap info, refactored