refactor(parser) abstract parser

Parser isn't suitable for this case, parse is a process, not a instance.
Parse function will match a local file from a url, containing any other attribute like wrap, pkg and so on.
The match will pass to many rules, break when matched, rule can be customize also

Closes #11
是不是这里有问题 https://github.com/spmjs/serve-spm/blob/0.6.0/lib/express.js#L33

那我先把 lowerCase 去掉