Add detailed smarty cache documentation to config

Instead of just making it availble document the smarty cache feature.

It might work for users, but it's advised to rely on the memcache
instead.

Fixes #309
Adding cache lifetime option to smarty config

* Renamed configuration array to `smarty` => `cache`
* Added `smarty` => `cache_lifetime` to expire cache files properly

This should be safe to use, be aware that each page request is cached!
That includes any POST/GET calls to the site.

It does help in speeding up the site, up to 100% on some requests. For a
high traffic site it probably makes sense to enable this option with a
low cache lifetime to ensure most recent data.

Addresses #309
adjust smarty configurations
Add detailed smarty cache documentation to config

Instead of just making it availble document the smarty cache feature.

It might work for users, but it's advised to rely on the memcache
instead.

Fixes #309
Adding `{nocache}` flags for dynamic content

This will update content instantly once the user changes it and not load
a cached version from the smarty cache.

Addresses #309
Adding cache detection to many pages

This will allow pages to skip loading data from backends like the
database or the wallet RPC server. If a cached page is detected and
valid, all dynamic content generation will be skipped completely.

Other pages that have not been adjusted in this commit will still fetch
backend data all the time. This will ensure clients always see the most
recent data, like worker information or account changes.

This should fix #309 completely but needs some testing.
disable smarty cache by default in dist
Disable caching check on Smarty globals

This will ensure data is available for those pages relying on global
data. A better step might be to load template specific data always on
the pages that require the data instead of relying on global data to be
available.

Fixes #309