- Port dkimsign.py to use argparse; now gives standard usage message and

is more extensible

README

@@ -11,7 +11,7 @@ signing and verification.
 
 VERSION
 
-This is dkimpy 0.6.2.
+This is dkimpy 0.7.0.
 
 REQUIREMENTS
 
@@ -19,6 +19,7 @@ REQUIREMENTS
    tested on python < 2.7 or python3 < 3.4, but may still work on python2.6
    and python 3.1 - 3.3.
  - dnspython or pydns. dnspython is preferred if both are present.
+ - argparse.  Standard library in python2.7 and later.
 
 INSTALLATION