v1.0.7

add upload files support (#51)

To upload file with test request you need to specify names and paths
 of files.
Don't forget specify Content-Type:
 > Content-Type: multipart/form-data

Example:

 - name: "upload-files"
   method: POST
   form:
       files:
         file1: "testdata/upload-files/file1.txt"
         file2: "testdata/upload-files/file2.log"
   headers:
     # case-sensitive, can be omitted
     Content-Type: multipart/form-data
   response:
     200: |
       {
         "status": "OK"
       }