Enhancements.

[dglancy]

Been on my queue for a while, so may no longer be that relevant. This code is in production for me though and works well.

1. Allow compiling and usage on iOS and OS X (previously was OS X only)
2. Fixed 15 memory leaks
3. Fixed [TKTumblr tumblelogs] to return an array of the users Tumblelogs. Introduced optional protocol delegate "(void)tumblrDidReturnTumblelogs:(NSArray *)tumblelogs"
4. Introduced an authenticate function and delegate callback to check if a users login/password is correct.