Additional fixes for UTF-8 surrogate escapes (#629)

* Fixes non UTF-8 surrogateescapes 

Surrogate escapes in Unicode (non UTF-8 encoding) will be properly escaped with backslashes when encountered, versus breaking the transport layer.

* Removes erroneous bytes decode and reraises

Fixes to re-raise exceptions with different reasons
Removes erroneous bytes decode where bytes are desired

* Adds test for surrogate escapes in body

Tests that a surrogate escape sequence is properly escaped
with backslashes to produce valid UTF-8.

* Use proper byte sequence for surrogate

* Use if/else versus pass

* Proper Unicode surrogate escape

Use a Unicode Surrogate that properly escapes in both Python2 and Python3

* Passing test once surrogatepass is used

Updating test to pass once surrogatepass is used

* Use surrogatepass instead of backslashreplace

This replicates behavior between Python 2 and Python 3

* Fixes whitespace

* Simplifies with no exception block

Since `surrogatepass` will only ever explicitly occur when there are surrogate bytes encountered, there is no need to let the error throw and catch it, also uses single-quotes for consistency.

* Fixes Unicode Surrogate Escapes in request logging

This is the same fix as accepted for ElasticSearch requests, except applied to the request logging mechanisms.

elasticsearch/connection/base.py

@@ -76,7 +76,7 @@ class Connection(object):
         # body has already been serialized to utf-8, deserialize it for logging
         # TODO: find a better way to avoid (de)encoding the body back and forth
         if body:
-            body = body.decode('utf-8')
+            body = body.decode('utf-8', 'ignore')
 
         logger.info(
             '%s %s [status:%s request:%.3fs]', method, full_url,
@@ -100,7 +100,7 @@ class Connection(object):
         # body has already been serialized to utf-8, deserialize it for logging
         # TODO: find a better way to avoid (de)encoding the body back and forth
         if body:
-            body = body.decode('utf-8')
+            body = body.decode('utf-8', 'ignore')
 
         logger.debug('> %s', body)