Revert "Pin Babel to <1.0 since it doesn't play well with pip 1.4"

Fixes bug 1205546.

This reverts commit adf074baa9d6876921b7dbbadae07006a7de6b5d.

Upstream Babel has worked around the pytz versioning issues by
releasing 1.1.

Change-Id: I2298c80ca0291ea6d0797194897ecc79ec50b818