API Additions

Better CORS support
- Added headers option to accept custom headers.  If you don't allow custom headers, any request with a custom header is rejected by Rack Cors.  I don't see accepting any header to be a security issue.  But if you needed to you could define a list of accepted custom headers.
- Added methods option to allow xhr requests to any verb.  If you don't define the accepted methods it defaults to only GET.

Updated history endpoint
- Added optional type parameter to allow all results, or only anime or manga
- Added scraping of manga
- Fixed scraping pattern from div#rightcontent_nopad to div#content