Use 'in' instead of deprecated has_key()

Use 'in' instead of deprecated has_key()

Since Python 2.2 'in' has been preferred to has_key() since it is
shorter, more readable, and faster. has_key() has been deprecated since
2.6 and was removed in 3.0.

See:
http://www.python.org/dev/peps/pep-0290/#testing-dictionary-membership

Mostly scripted with
sed -i -e 's/if \(not \)\?\(.*\)\.has_key(\(.*\))/if \3 \1in \2/'