Remove the test_<os>.rb files.  Add a selftest.rb

test/test_<os>.rb are redundant with the unit tests.
Added selftest.rb, which prints the ifconfig data available on the
running system; not from the test fixtures.
Added parsing for interface capabilities

lib/ifconfig/bsd/interface_types.rb
	Parse the "options=" or "enabled=" line.

lib/ifconfig/common/interface_types.rb
	Display capabilities in NetworkAdapter.to_s

ifconfig_examples/dragonflybsd.txt
test/unit/tc_dragonflybsd.rb
	Add test case using output format of DragonFlyBSD 3.6.0.

ifconfig_examples/netbsd.txt
test/unit/tc_netbsd.rb
	Add test case using output format of NetBSD 6.0.

test/unit/tc_freebsd.rb
	Add test case using data already present in the fixture.
Fix Ruby warnings.