bad argument handling

[qraynaud]

In index.js, in the first line of the staticCAche function, there is:

if (typeof dir === 'object') {
  options = dir
  files = options
  dir = null
}

this is wrong because options is lost before being copied to files. this should be:

if (typeof dir === 'object') {
  files = options
  options = dir
  dir = null
}

[dead-horse]

PR ?

[qraynaud]

I don't have time to do this right now. I'll post here when I start if noone does it before me :-).