Generate constraints file to pin deps in Docker images

Dockerfiles pin versions using constraints file

Pulling out strip_hashes and add --no-deps flag

tools/strip_hashes.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python
+
+import os
+import re
+import sys
+
+def main(args):
+    out_lines = []
+    for line in args:
+        search = re.search(r'^(\S*==\S*).*$', line)
+        if search:
+            out_lines.append(search.group(1))
+    return os.linesep.join(out_lines)
+
+if __name__ == '__main__':
+    print(main(sys.argv[1:]))