[BUG] PHP client cannot post model (json)

[wing328]

Tested with the latest PHP client (SwaggerClient) and it failed to post model (addPet). tcpdump shows that it interrupts the model (json) as multi-form parameters:

POST /v2/pet HTTP/1.1
User-Agent: PHP-Swagger
Host: petstore.swagger.io
Accept: application/json, application/xml
Content-Length: 632
Expect: 100-continue
Content-Type: application/json; boundary=------------------------00c9a929dcb67f70
{P6E
Qw(?
{66E
Qw(?
HTTP/1.1 100 Continue
Qw(`=
Qw(`=
--------------------------00c9a929dcb67f70
Content-Disposition: form-data; name="id"
10005
--------------------------00c9a929dcb67f70
Content-Disposition: form-data; name="category"
--------------------------00c9a929dcb67f70
Content-Disposition: form-data; name="name"
PHP Unit Test
--------------------------00c9a929dcb67f70
Content-Disposition: form-data; name="photo_urls"
--------------------------00c9a929dcb67f70
Content-Disposition: form-data; name="tags"
--------------------------00c9a929dcb67f70
Content-Disposition: form-data; name="status"
--------------------------00c9a929dcb67f70--
,THTTP/1.1 400 Bad Request
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET, POST, DELETE, PUT
Access-Control-Allow-Headers: Content-Type, api_key, Authorization
Content-Type: application/json
Connection: close
Server: Jetty(9.2.7.v20150116)
{"code":400,"type":"unknown","message":"bad input"}

Form POST (updatePetWithForm) request looks good with the correct content-type and body

POST /v2/pet/10005 HTTP/1.1
User-Agent: PHP-Swagger
Host: petstore.swagger.io
Accept: application/json, application/xml
Content-Type: application/x-www-form-urlencoded
Content-Length: 29
name=test%251&status=test%252

I'll try to fix the issues and add some test cases to cover both POST form and model (JSON)

[wing328]

PR merged