Always restart NGINX

If you use VVV's auto-site-setup feature, new sites create nginx configuration files that are not read by nginx unless restarted. This makes sure that we don't need to provision to make scaffold-ed sites work.
Remove the last nginx restart in favor of the always-done restart in Vagrantfile
Remove hosts from /etc/hosts on suspend
Update Composer packages on every provision

In #129, we moved from a composer.json to a global configuration
for packages such as phpunit. In the current state, changing the
version numbers for these packages only modifies new boxes.

Instead, we can check for and install Composer separately from
a self update and a global update. This allows version changes
to be applied with a standard `vagrant provision`.
global bin-dir is required for Composer packages
Upgrade PHPUnit to 4.3.x
Remove duplicate config of Composer bin-dir
Merge pull request #492 from Varying-Vagrant-Vagrants/composer-provision

[PR] Allow Composer packages to update on `vagrant provision`
Added external ip sample
Rework wording for external IP address example

See #395
Merge branch 'pr/395'

Fixes #395
Merge pull request #491 from miya0001/remove-hosts-on-suspend

Remove hosts from /etc/hosts on suspend
switching to apt-key so that we can use port 80 to get around a restrictive proxy
see this post: http://superuser.com/questions/64922/how-to-work-around-blocked-outbound-hkp-port-for-apt-keys
Removed commented out lines
Retrieve the signing key for Nginx from nginx.org

The key we were using is way outdated from when we actually used
the Ubunto repositories for nginx. We can grab the signing key
from Nginx on the fly and apply it before installing.
Provide output beyond generated "OK" for nginx signing key
Clean up processing of nodejs signing key
Merge pull request #495 from Varying-Vagrant-Vagrants/pr/446

[PR] Clean up GPG signing key handling

Fixes #446
Fix the ability to generate call graph images with Webgrind and graphviz.

Webgrind's default config sets the path for graphviz to /usr/local/bin/dot, and during provisioning, apt-get installs graphviz to /usr/bin/dot. So the proposal here is to simply symlink /usr/local/bin/dot to /usr/bin/dot -- without which you can't currently generate call graphs in Webgrind.
Update docs around Graphviz symlink