Http response branch

Http Response part has been implemented
#### Date header:
**Definition**
```
Date - The date and time that the message was sent (in "HTTP-date" format as defined by RFC 7231)	
```
**Example:** 
```
Date: Tue, 15 Nov 1994 08:12:31 GMT
```
(reference: http://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Response_Headers)

Does ToString() return the same format of date time?