The time string looks like OData version 2 JSON verbose format for Datetime that may be seen in old ASP.NET or WCF applications:
“/Date(<ticks>[“+” | “-” <offset>])/”
  <ticks> = number of milliseconds
  since midnight Jan 1, 1970
  <offset> = utc offset
#!/usr/bin/env python3
import re
from datetime import datetime, timedelta, timezone
time_string = u"/Date(1409522400000+0200)/"
epoch = datetime(1970, 1, 1, tzinfo=timezone.utc)
ticks, offset = re.match(r'/Date\((\d+)([+-]\d{4})?\)/$', time_string).groups()
utc_dt = epoch + timedelta(milliseconds=int(ticks))
print(utc_dt)
if offset:
   offset = int(offset)
   hours, minutes = divmod(abs(offset), 100)
   if offset < 0:
      hours, minutes = -hours, -minutes
   dt = utc_dt.astimezone(timezone(timedelta(hours=hours, minutes=minutes)))
   print(dt)
Output
2014-08-31 22:00:00+00:00
2014-09-01 00:00:00+02:00
where timezone is defined here.