Cleanup and dynamic SHA 256

• Remove unnecessary code (thanks @kostyrevaa)
• Determine package's SHA 256 from releases.hashicorp.com (for #16)
• Update documentation

Update var names

v1.5.6

Update var names

Now with moar idempotency like behaviors!

• Initial attempts at idempotency in main tasks (for #14, #15)
• Update README

Recursors environment variable

v1.5.4

Recursors env

Update start_join

• Update start_join for client configuration template

Consul 0.7.1 and template changes

• Consul version 0.7.1
• Consistent template names
• Update documentation

Fail if consul_iface not found

• Fail when ethernet interface specified by consul_iface not found on
  the system (addresses #13)

Initial TLS support

• Add initial TLS support
• Update documentation

Dnsmasq, iptables, gossip encryption, and docs updates

• Move Dnsmasq restart to inside of tasks
• Add client dependencies for further configuration (thanks @crumohr)
• Fix error using predefined encryption key (thanks @crumohr)
• Removal of redundant includes (thanks @crumohr)

Numerous features and improvements

• Compatibility with Ubuntu 16.04 (thanks @crumohr)
• iptables support (thanks @crumohr)
• Booleans instead of strings for variables (thanks @crumohr)
• Runnable if DNS is broken (thanks @crumohr)
• Remove unused variables
• Update block conditional for ACLs
• Update documentation