Omit headers & field metas only in multipart/form-dasta

[anquegi]

Since I saw this two issues which are the same:

https://github.com/fukamachi/ningle/issues/22 https://github.com/fukamachi/ningle/issues/24

I thik that the best way is to check if the body is multipart/form-data, from here

http://www.iana.org/assignments/media-types/media-types.xhtml

Maybe should be use match against regular expression or substring, I use string-equal in order to be case-insentive as request headers are, and I do not feel that to add more complexity will be good for this purpouse

http://stackoverflow.com/questions/5258977/are-http-headers-case-sensitive

I hope this helps

[fukamachi]

Looks good. Thanks!