Fixed chunk_size values in iter_content() and iter_lines()

Following discussion about issue #539 Kenneth agreed that a default
`chunk_size` of 1 for `iter_lines()` would make more sense, but
apparently changed `chunk_size` for `iter_content()` by mistake
instead, which did solve the `iter_lines()` issue but also changed the
default `iter_content()` chunk to 1 bytes which is not desirable.

Author: Marco Ponton

requests/models.py

@@ -705,7 +705,7 @@ def ok(self):
             return False
         return True
 
-    def iter_content(self, chunk_size=1, decode_unicode=False):
+    def iter_content(self, chunk_size=10 * 1024, decode_unicode=False):
         """Iterates over the response data.  This avoids reading the content
         at once into memory for large responses.  The chunk size is the number
         of bytes it should read into memory.  This is not necessarily the
@@ -731,7 +731,7 @@ def generate():
 
         return gen
 
-    def iter_lines(self, chunk_size=10 * 1024, decode_unicode=None):
+    def iter_lines(self, chunk_size=1, decode_unicode=None):
         """Iterates over the response data, one line at a time.  This
         avoids reading the content at once into memory for large
         responses.