Removes BC breaking PDP version

PDP 1.4.* introduced a BC breaking change (requires mbstring and intl)
without incrementing the major version.  1.3.1 is the most recent 1.3
version.
Removes tests incompatable with PHP < 1.4
Merge pull request #34 from jeremykendall/fix/remove-bc-breaking-pdp-version

Removes BC breaking pdp version