tumblr_backup: use double quotes for strings containing english

That's just my convention, but I like it :-)

Single-quoted strings are technical and not translateable.
tumblr_backup: fix a syntax error in Python 2.7

Fixes #46
Delete delicious_import.py

It's obsolete. Delicious now produces RSS feeds that can be posted
directly with tumblr.py.
Merge branch 'master' into api-v2