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.
Since plenty scrypt based currencies are supported, changed error
message to say `wallet` instead of `litecoind` when failing to connect
to RPC service.
* Currently no GUI, use DB access to change the row entry
* Upgraded Database table `accounts` with upgrade SQL
* Updated `admin` field to `is_admin` as boolean
* Modified pages, classes, templates to support is_admin and is_locked
Addresses #147
