oft: fix padding of msecs log field
per-test logfiles

The new --log-dir option creates a directory with one log file for every test
(plus main.log for the oft script). It takes precedence over the --log-file
option if both are specified.

The --log-append option and the ability to pass "-" or "stderr" to --log-file
have been removed.
add a simple pcap file writer
pcap_writer: use PPI
use PcapWriter to log dataplane traffic

When we write a logfile we'll also write a pcap file with the extension
replaced by ".pcap". If per-test logging is enabled we'll open a new pcap file
for each test.
Merge into master from pull request #67:
per-test log files (https://github.com/floodlight/oftest/pull/67)
Merge into master from pull request #68:
built-in pcap captures (https://github.com/floodlight/oftest/pull/68)
Support for specifying interface name while creating virtual port.
Reorganized virtual port interface name in vport create message.
Merge into master from pull request #69:
Support for specifying interface name while creating virtual port. (https://github.com/floodlight/oftest/pull/69)
testutils: fix undefined variable in packet_in_match
testutils: add new functions to check for dataplane packets

`receive_pkt_check` and `receive_pkt_verify` had slightly different
functionality and neither were sufficient for complex tests. This change
deprecates them and adds new functions.

The high level `verify_packets` function is sufficient for most tests. When
more complex logic is needed the primitive functions `verify_packet`,
`verify_no_packet`, and `verify_no_other_packets` should be used directly.

All OpenFlow 1.0/1.3 tests are updated to use the new functions. The old
functions are left around for compatibility with out of tree tests.
testutils: use idiomatic ternary operator in flow match tests functions
Merge into master from pull request #70:
testutils improvements (https://github.com/floodlight/oftest/pull/70)
testutils: fix flow_match_test when exp_pkt is None

This fixes a bug introduced in e4b384df, which removed code it shouldn't have.

Reported by Tony van der Peet.
Merge into master from pull request #71:
testutils: fix flow_match_test when exp_pkt is None (https://github.com/floodlight/oftest/pull/71)
oft: change default port to 6653

6653 is the IANA assigned port number.
add OF 1.3 flow_stats test module
flow_stats-1.3: add a test for matching on cookie
flow_stats.CookieFlowStats: include random cookies/masks