TS-2531: add a nohost_rule check for proxy request

This change is used to solve the problem TS-2531. 

Below is my test method:

config remap.config as below:  (127.0.0.1:8885 is my backend server.)
```
map / http://127.0.0.1:8885/
```
Before I added this change, when I send a ``GET http://localhost/test`` to ATS, it returns 404 not found.
```
GET http://localhost/test HTTP/1.1

HTTP/1.1 404 Not Found
```

The root reason is that ATS doesn't check no host rules for this requests which contain host, and these 
requests can not be matched the rule ``map / http://127.0.0.1:8885/`` .

So I moved these check logic to outside, now ATS can return 200 response.

```
GET http://localhost/test HTTP/1.1

HTTP/1.1 200 OK
```
Now , a 200 OK response returns.