Allow url option that's forwarded to ioredis

[jgodson]

Fix for #64 and allows passing a url in the options for koa-redis (url was not a valid option in v4.0.0, though it's mentioned in the readme still). This change also makes it backwards compatible with 3.

If present, this is passed to ioredis as the first argument, with the other options as the second argument see here for details

new Redis([port], [host], [options])

[port] - Port of the Redis server, or a URL string(see the examples below), or the options object(see the third argument).

[host] - Host of the Redis server, when the first argument is a URL string, this argument is an object represents the options.

This allows ioredis to parse the url string instead of forcing you to pass each parameter separately.

As an example:

redisStore({
  url: 'redis://user:password@redis-service.com:6379/'
})

would be the equivalent of new Redis('redis://user:password@redis-service.com:6379/'); in ioredis

[coveralls]

Coverage increased (+0.05%) to 97.391% when pulling 841c46f on jgodson:master into 118943e on koajs:master.

[dead-horse]

can you add a test case for this feature ?

[jgodson]

@dead-horse done!

[jgodson]

@dead-horse any chance you could have a look at this?

[jgodson]

Or maybe @niftylettuce, could you 👀 by any chance?

[niftylettuce]

v4.0.1 released to npm