Set server hostname to {stage}.{domain}, as necessary

Note this involves first passing stage into provisioning script (and subsequently into playbook), then updating /etc/host{s,name} and running `hostname`
As a counterpart to `deploy:setup`

Fixes #6
So *maybe* a good idea to prompt beforehand
Merge branch 'master' into 40-set-hostname
Bypass hostname checks if stage is not defined (eg, running `vagrant provision` directly)
Simplified varnish cookie cleanup rules

* Removed cleanup of 'has_js' (remnant of drupal stuff from vcl template)
* Removed specific cookie checks, instead removing any underscore prefixed
* Left in removal of Google Analytics "utm" prefixed cookies (debateable, @ericclemmons might have opinion here)

Fixes #28 but more vcl cleanup to do...
Simplified cookie logic in receive/wordpress.vcl

* The existing wp cookie check was *starting with* `wp-` or `wprdpress_`, but would not match a 2nd or higher position wp cookie
* The second url check for `wp-(login|admin)` was no longer necessary, so removing all cookies past that point is more efficient
Removed extra GA cookie checks (turned out to be components of __utmz, not cookies themselves)
Updated to use `hostname` and `replace` modules

Both modules should be (hopefully) in ansible's 1.4 release, until then providing them here as custom lib modules:

* hostname module, see ansible/ansible#3940
* replace module, see ansible/ansible#4889
Switch varnish from malloc to file caching backend

Fixes #53
Documented genesis:teardown
Removed cache bypass for local.* hostname
Merge branch 'master' into 40-set-hostname
Replace manual passing of stage with use of ansible_fqdn fact
Added unattended install of postfix. Fixes #37

Could potentially add two things here:

* template for /etc/aliases, where user can define an off-server email to which any system emails should be sent
* template for /etc/postfix/main.cf, with optional support to relay to external smtp server (eg: gmail)
Added mail.postmaster var and /etc/aliases template

See http://www.feep.net/sendmail/tutorial/intro/aliases.html
Remove caching for static files
Revert "Replace manual passing of stage with use of ansible_fqdn fact"

This reverts commit 09cf623b0f43e4224fea20823e87b12604d9d1a8.
Removed custom hostname module (after 1.4 release), misc cleanup of common tasks
Fixed typo in PHP ini for date.timezone (missing closing quote)