A quick python script to convert all dates to unix time.

date_converter.py

#!/usr/bin/python
import os, sys
import dateutil
import dateutil.parser
import time
import calendar
import fileinput

for line in fileinput.input(inplace=1):
    if 'date: ' in line:
        old = line.lstrip("date: ").rstrip("\n")
        old_mod = old + " PST"
        d = dateutil.parser.parse(old_mod, fuzzy=True)
        t = time.strptime(d.ctime())
        new = time.mktime(t)
        line = "date: " + str(new)
        print line
    else: 
        print line