Fix test case prep
Do not use tuples for the `set` operation

Also increase git change visibility on API export changes by giving each
function its own line.
Add `expire` API function for easily setting TTL values on keys
Do not implicitly use `create_key`; have calling modules invoke it as necessary

It may be inappropriate to assume that lists should be run through `create_key`
before a command is executed, so we leave this decision to calling modules
instead. It's safer and more explicit.
Use native multi-key delete Redis query

The only downside to this change is that passing a list of keys now requires the
calling module to know about the location of the keys. If the command is
executed on a particular Redis instance but one or more of the keys do not exist
there, then those keys simply aren't deleted. Thankfully the return value is a
number representing how many keys were affected, so any number that doesn't
match with the original length of the list means there are keys that either
didn't exist at all or didn't exist on the Redis instance where the command was
executed.