Updating subprocess.pyi to support python 3.5 (#438)

* Updating subprocess.pyi to support python 3.5 

Also added DEVNULL which was added in 3.3

* Incorrectly checked sys.version_info

* Addressed travis build failures

Forgot that __init__ should return None and also forgot "self" on a method. Like a dummy.

stdlib/3/subprocess.pyi

@@ -3,7 +3,42 @@
 # Based on http://docs.python.org/3.2/library/subprocess.html
 
 import sys
-from typing import Sequence, Any, Mapping, Callable, Tuple, IO, Optional, Union
+from typing import Sequence, Any, Mapping, Callable, Tuple, IO, Optional, Union, List
+
+
+if sys.version_info >= (3, 5):
+    class CompletedProcess:
+        args = ...  # type: Union[List, str]
+        returncode = ... # type: int
+        stdout = ... # type: Union[str, bytes]
+        stderr = ... # type: Union[str, bytes]
+        def __init__(self, args: Union[List, str], 
+                     returncode: int, 
+                     stdout: Union[str, bytes], 
+                     stderr: Union[str, bytes]) -> None: ...
+        def check_returncode(self): ...
+    
+    # Nearly same args as Popen.__init__ except for timeout, input, and check
+    def run(args: Union[str, Sequence[str]],
+	    timeout: int = ...,
+	    input: Union[str, bytes] = ...,
+	    check: bool = ...,
+	    bufsize: int = ...,
+	    executable: str = ...,
+	    stdin: Any = ...,
+	    stdout: Any = ...,
+	    stderr: Any = ...,
+	    preexec_fn: Callable[[], Any] = ...,
+	    close_fds: bool = ...,
+	    shell: bool = ...,
+	    cwd: str = ...,
+	    env: Mapping[str, str] = ...,
+	    universal_newlines: bool = ...,
+	    startupinfo: Any = ...,
+	    creationflags: int = ...,
+	    restore_signals: bool = ...,
+	    start_new_session: bool = ...,
+	    pass_fds: Any = ...) -> CompletedProcess: ...
 
 # Same args as Popen.__init__
 def call(args: Union[str, Sequence[str]],
@@ -64,6 +99,9 @@ def check_output(args: Union[str, Sequence[str]],
 # TODO types
 PIPE = ... # type: Any
 STDOUT = ... # type: Any
+if sys.version_info >= (3, 3):
+    DEVNULL = ... # type: Any
+
 
 class CalledProcessError(Exception):
     returncode = 0