fix resolved relative urls for windows

[mankdev]

Plugin uses module "path" for building result relative url. But on windows platform it use '//' as path separator. So on windows we get urls that can't be understand by browsers.

[cakeinpanic]

@mankdev I think it should be separate method with speaking name

[mankdev]

@cakeinpanic please take a look

BTW I suppose that we should split processUrlRebase function body into several functions, because now, it makes a lot of action: url resolving, renaming. If you agree please create separate task

[cakeinpanic]

@mankdev i agree with you, but there is no need in standalone issue, i'll do it within #3