website/www: feature preview blog post: rsync
website/www: ignore the standalone archive page
website/www: force up the version
website/www: fix downloads
core: Modify Bundler settings to work with restricted permissions

This includes two changes:

1. Change the Vagrant requirement to use the "= VERSION" constraint.
   The "path:" previously requires write permission in the directory
   of the gemspec, which we don't have in installers.

2. Set a BUNDLE_APP_CONFIG and BUNDLE_PATH setting. By setting this,
   Bundler won't ask for sudo password. Bundler never actually needs it;
   it is just overly aggressive in thinking it does.
core: chomp the version so we can echo into it
core: poll for process exit on SSH#exec with subprocess
core: make sure any Subprocess exits no matter what
guests/linux: public key insertion is more robust

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