clean up usage
core: Machine#with_ui
core: Prefixed UI only requests bolding if not specified at instance-level
core: Environment#lock tests
core: fix Environment tests
core: Ui#dup works properly
core: Ui::Prefixed can take prefix_spaces option
core: Ui::Prefixed values instance-level opts
providers/virtualbox: config to skip guest additions check
Fixing ssh_config proxy_command is not included
Remove website/ dir from gem [GH-2951]
Merge pull request #2950 from elyast/master

command/ssh-config: Fixing ssh_config, proxy_command is not included
Update CHANGELOG
Merge pull request #2948 from gnawhleinad/master

command/*: clean up usage
kernel/v2: capture error if provider config is bad [GH-2959]
core: Machine can set box
core: keep the same UI when handling a box URL
core: HandleBox keeps the same machine instance
website/www: feature preview blog post: rsync
website/www: ignore the standalone archive page