Fix encrypting to filenames and/or file-like objects.

* FIXES Issue#24, which prevented python-gnupg from encrypting to a
   filename given as a string to the `output` parameter of
   `gnupg.GPGMeta._encrypt()`.

 * THANKS TO by Bill Buddington of SecureDrop and Yan Zhu of the
   Electronic Frontier Foundation (EFF) for finding and reporting the
   bug. The ticket for this bug can be viewed at:
   https://github.com/isislovecruft/python-gnupg/issues/24

gnupg/_meta.py

@@ -766,10 +766,10 @@ class GPGBase(object):
                                   **recipients** keys. If False, display trust
                                   warnings. (default: True)
 
-        :param str output: The output file to write to. If not specified, the
-                           encrypted output is returned, and thus should be
-                           stored as an object in Python. For example:
-
+        :type output: str or file-like object
+        :param output: The output file to write to. If not specified, the
+                       encrypted output is returned, and thus should be stored
+                       as an object in Python. For example:
 
         >>> import shutil
         >>> import gnupg
@@ -808,17 +808,23 @@ class GPGBase(object):
         """
         args = []
 
+        ## FIXME: GnuPG appears to ignore the --output directive when being
+        ## programmatically driven. We'll handle the IO ourselves to fix this
+        ## for now.
+        output_filename = None
         if output:
             if getattr(output, 'fileno', None) is not None:
                 ## avoid overwrite confirmation message
-                if getattr(output, 'name', None) is None:
-                    if os.path.exists(output):
-                        os.remove(output)
-                    args.append('--output %s' % output)
-                else:
+                if getattr(output, 'name', None) is not None:
+                    output_filename = output.name
                     if os.path.exists(output.name):
                         os.remove(output.name)
-                    args.append('--output %s' % output.name)
+                    #args.append('--output %s' % output.name)
+            else:
+                output_filename = output
+                if os.path.exists(output):
+                    os.remove(output)
+                #args.append('--output %s' % output)
 
         if armor: args.append('--armor')
         if always_trust: args.append('--always-trust')
@@ -877,4 +883,12 @@ class GPGBase(object):
         self._handle_io(args, data, result,
                         passphrase=passphrase, binary=True)
         log.debug("\n%s" % result.data)
+
+        if output_filename:
+            log.info("Writing encrypted output to file: %s" % output_filename)
+            with open(output_filename, 'w+') as fh:
+                fh.write(result.data)
+                fh.flush()
+                log.info("Encrypted output written successfully.")
+
         return result