Copy file from http without read it in one time

When huge payload was read, it could cause Out Of Memory error.
Use istools copyfileobj for read chunk by chunk.

Signed-off-by: Seblu <sebastien.luttringer@smartjog.com>

installsystems/tools.py

@@ -60,7 +60,7 @@ def copy(source, destination, uid=None, gid=None, mode=None, timeout=None):
     elif (stype == "http" or stype == "ftp") and dtype == "file":
         f_dest = open(destination, "w")
         f_source = urllib2.urlopen(source, timeout=timeout)
-        f_dest.write(f_source.read())
+        copyfileobj(f_source, f_dest)
     elif stype == "file" and dtype == "":
         raise NotImplementedError
     else: