Query parameter validation should return an explicit error when skip value is a negative integer

Steps to reproduce:

1. Install beer-sample database
2. Go to view 'brewery_beers' and while doing view query change the skip to -2(a negative number).
Attached page is displayed which shows webpage is unavailable. We can change it to something similar when limit is negative e.g.

{"error":"query_parse_error","reason":"Invalid value for positive integer parameter: \"-10\""}

negative LIMIT Query
bash> curl -v -s 'http://127.0.0.1:9500/beer-sample/_design/beer/_view/brewery_beers?connection_timeout=60000&skip=2&limit=-10'

• About to connect() to 127.0.0.1 port 9500 (#0)
• Trying 127.0.0.1... connected
• Connected to 127.0.0.1 (127.0.0.1) port 9500 (#0)
  > GET /beer-sample/_design/beer/_view/brewery_beers?connection_timeout=60000&skip=2&limit=-10 HTTP/1.1
  > User-Agent: curl/7.21.4 (x86_64-unknown-linux-gnu) libcurl/7.21.4 OpenSSL/1.0.1 zlib/1.2.3.4
  > Host: 127.0.0.1:9500
  > Accept: /
  >
  < HTTP/1.1 400 Bad Request
  < Server: MochiWeb/1.0 (Any of you quaids got a smint?)
  < Date: Wed, 07 Nov 2012 10:04:14 GMT
  < Content-Type: text/plain;charset=utf-8
  < Content-Length: 95
  < Cache-Control: must-revalidate
  < {"error":"query_parse_error","reason":"Invalid value for positive integer parameter: \"-10\""}
• Connection #0 to host 127.0.0.1 left intact
• Closing connection #0

negative SKIP Query
bash> curl -v -s 'http://127.0.0.1:9500/beer-sample/_design/beer/_view/brewery_beers?connection_timeout=60000&skip=-2&limit=10'

• About to connect() to 127.0.0.1 port 9500 (#0)
• Trying 127.0.0.1... connected
• Connected to 127.0.0.1 (127.0.0.1) port 9500 (#0)
  > GET /beer-sample/_design/beer/_view/brewery_beers?connection_timeout=60000&skip=-2&limit=10 HTTP/1.1
  > User-Agent: curl/7.21.4 (x86_64-unknown-linux-gnu) libcurl/7.21.4 OpenSSL/1.0.1 zlib/1.2.3.4
  > Host: 127.0.0.1:9500
  > Accept: /
  >
  < HTTP/1.1 200 OK
  < Transfer-Encoding: chunked
  < Server: MochiWeb/1.0 (Any of you quaids got a smint?)
  < Date: Wed, 07 Nov 2012 10:03:58 GMT
  < Content-Type: text/plain;charset=utf-8
  < Cache-Control: must-revalidate
  <
• Received problem 2 in the chunky parser
• Closing connection #0