Support IPv6 access address for Openstack

We still prefer the IPv4 address, but if there is an IPv6 address and no IPv4 address, use IPv6.
builder/openstack: don't hardcode "DFW" and make region required
website: document required openstack region setting
website: fixup some underscores to not be emphasis in the AWS docs
website: add openstack to the intro platforms list
builder/openstack: region is now required
Increase default SSH timeout for OpenStack from 1m -> 5m

Many cloud providers have a minimum charge of 1 hour, and if there are DNS problems we can hit the 1 minute timeout easily.

Waiting five minutes gives more of a margin of error.
Merge pull request #378 from justinsb/increase_ssh_timeout

builder/openstack: Increase default SSH timeout from 1m -> 5m
Fix typo

s/Detatching/Detaching/
Merge pull request #381 from greenalto/typo

builder/vmware: fix typo
Merge pull request #379 from justinsb/justinsb-openstack_ipv6_support

builder/openstack: Support IPv6 access address for Openstack
Update CHANGELOG
v0.3.6
Allow the Openstack project to be specified

It isn't actually optional, according to the spec
Only pass the project if it is specified
up version for dev
command/inspect: fix weird output
Merge pull request #382 from justinsb/specify_openstack_project

builder/openstack: allow project to be specified
website: update website
Update CHANGELOG