Idiot proof TOTP enabling.

Make sure TOTP is working before enabling it.
Update README.md with prerequisites and missing setup steps.
Add some additional config variables to the example conf file.
Slightly beter handling of TOTP challenge code.

This would previously give errors if the user entered a non-numeric TOTP code.
Merge pull request #4 from mrmonday/list-prerequisites

Update README.md with prerequisites and missing setup steps.
Merge pull request #5 from mrmonday/conf-vars

Add some additional config variables to the example conf file.
Merge pull request #3 from mrmonday/safe-otp-enable

Idiot proof TOTP enabling.
Merge pull request #6 from mrmonday/totp-challenge-validation

Slightly beter handling of TOTP challenge code.
vps: generate proper boot parameters when an ipnet is missing
notifications: use random nonce to ensure we do not get served a cached version
vps/models: indentation fixes (don't mix tab/space)
vps/models.py: allow VPS init if we have any IP

Currently, if no IPv4 addresses are available for a VPS, the VPS will
not be initialised at all and it will 'fail fast'.  This patch will
allow a VPS to run with only a IPv6 address.
nodestats: UI tweaks
vps: add admin UI for adding new nodes
dns: add support for SSHFP and LOC record types
Merge pull request #7 from Centarra/vps-allow-v6-only

vps/models.py: allow VPS init if we have any IP
templates: support multiple brands
status: use breakln instead of nl2br
support: add some hooks for templaters
vps: update user experience to match mod_branding_centarra (will backport backwards-compat shim next)