Add telnet to the base server install

This allows us to test things like memcached from the terminal
Set the default WP_DEBUG to false in production, true in dev
Setting a default theme causes some annoyance

A theme needs to be set anyway, that should happen after installation.
Salt the object cache key if cache_key is defined in sites.sls
Fill in nonces dynamically if available in sites.sls
If a default theme is specified in sites.sls, use it
Move advanced cache definition to a batcache block, document
Improve documentation throughout the wp-config jinja template
Merge pull request #52 from washingtonstateuniversity/prod-29

[PR] Additional fixes from production