oft: Add support for XML output

Add support for xUnit-format XML output by utilising the 'xmlrunner'
package. This feature is optional, and is disabled by default.

Resolves issue #123.

Signed-off-by: Stephen Finucane <stephenfinucane@hotmail.com>
oft: Move profiler setup/teardown to function

Profiler setup/teardown was done "in-situ". This was inconsistent
with the general design of 'oft'. Fix this, by moving these
operations to a seperate file.

In addition, add a '--profile-file' parameter, so that the output
file can be changed if necessary.

Signed-off-by: Stephen Finucane <stephenfinucane@hotmail.com>
verify_packet_in with in_port as None.
Merge into master from pull request #130:
verify_packet_in with in_port as None. (https://github.com/floodlight/oftest/pull/130)
oft: Enclose 'xmlrunner' import in try-except

If the 'xmlrunner' package cannot be imported, an exception is
thrown. Unhandled, the datapath will not shut down causing the
program to hang. Ensure the datapath is killed before re-raising
the exception.

Signed-off-by: Stephen Finucane <stephenfinucane@hotmail.com>
Merge into master from pull request #129:
Add XML support (https://github.com/floodlight/oftest/pull/129)
update pyloxi and add tcp flags support
remove tab
Merge into master from pull request #131:
update pyloxi and add tcp flags support (https://github.com/floodlight/oftest/pull/131)
bsn_flow_checksum: add TableChecksumIds test

We had a bug in Indigo where the table ID wasn't being populated in the table
checksum stats reply. This test would have caught it.
Merge into master from pull request #132:
bsn_flow_checksum: add TableChecksumIds test (https://github.com/floodlight/oftest/pull/132)
update pyloxi to loxigen-artifacts @ c5aa7c7e694f3679b53f92844eb955d74719ca95
Merge into master from pull request #133:
update pyloxi to loxigen-artifacts @ c5aa7c7e694f3679b53f92844eb955d7471... (https://github.com/floodlight/oftest/pull/133)
add new port counters
Merge into master from pull request #134:
add new port counters (https://github.com/floodlight/oftest/pull/134)
bsn_flow_checksum: change checksum XOR operation to add/subtract
bsn_gentable: change checksum XOR operation to add/subtract
Merge into master from pull request #135:
Replace flowtable/gentable checksum XOR operations with add/subtract (https://github.com/floodlight/oftest/pull/135)
tests-1.3: mark bsn_in_ports as nonstandard

This tests an experimenter OXM.
Merge into master from pull request #136:
tests-1.3: mark bsn_in_ports as nonstandard (https://github.com/floodlight/oftest/pull/136)