[copyright] add MIT License copyright header to remaining Python files

contrib/devtools/security-check.py

@@ -1,4 +1,7 @@
 #!/usr/bin/env python
+# Copyright (c) 2015-2016 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
 '''
 Perform basic ELF security checks on a series of executables.
 Exit status will be 0 if successful, and the program will be silent.

contrib/devtools/test-security-check.py

@@ -1,4 +1,7 @@
 #!/usr/bin/env python2
+# Copyright (c) 2015-2016 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
 '''
 Test script for security-check.py
 '''

share/qt/extract_strings_qt.py

@@ -1,4 +1,7 @@
 #!/usr/bin/env python
+# Copyright (c) 2012-2016 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
 '''
 Extract _("...") strings for translation and convert to Qt stringdefs so that
 they can be picked up by Qt linguist.