Set the full timestamp including the date in the result pcap file

- Parse the timestamp with a regular expression.
- Call tshark with -te option to print the time in seconds since epoch
  (Jan 1, 1970 00:00:00)
- Call text2pcap with '%s.' time format string
Merge pull request #2 from velichkov/timestamp

Set the full timestamp including the date in the result pcap file