enable py3 thrift language

Summary:
The old `py` Thrift language support doesn't correctly handle string
vs. bytes, which causes an exception to be thrown when deserializing
paths or blobs that aren't UTF-8.

We will eventually want to migrate to the py3 language implementation,
which supports streaming.

Reviewed By: genevievehelsel

Differential Revision: D21693082

fbshipit-source-id: 0ea10fd3960f5acba353bccb83b5cf539e7eeffb

eden/fs/config/eden_config.thrift

@@ -8,6 +8,7 @@
 namespace cpp2 facebook.eden
 namespace java com.facebook.eden.thrift
 namespace py facebook.eden.eden_config
+namespace py3 eden.fs.config
 
 /**
  * ConfigSource identifies the point of origin of a config setting.

eden/fs/service/eden.thrift

@@ -11,6 +11,7 @@ include "fb303/thrift/fb303_core.thrift"
 namespace cpp2 facebook.eden
 namespace java com.facebook.eden.thrift
 namespace py facebook.eden
+namespace py3 eden.fs.service
 
 /** Thrift doesn't really do unsigned numbers, but we can sort of fake it.
  * This type is serialized as an integer value that is 64-bits wide and

eden/fs/service/streamingeden.thrift

@@ -7,6 +7,7 @@
 
 include "eden/fs/service/eden.thrift"
 namespace cpp2 facebook.eden
+namespace py3 eden.fs.service
 
 /** This file holds definitions for the streaming flavor of the Eden interface
  * This is only available to cpp2 clients and won't compile for other