Error handling conforms to Python 2.7 and 3.4.

before:
- except Exception, e
- raise Exception, "message"
- lambda (x, y)

after:
- except Exception as e
- raise Exception("message")
- lambda x, y
Python 3 support: stop using izip()
Python 3 support: print() vs print
Python 3 support: lambdas & tuple unpacking
pattern.web: fix truncated twitter messages