Fix OF-Config record definitions.
Fix default connection behaviour for logical switch.
Don't include undefined elements in encoded XML.
Add decoding of operation attribute
Introduced ability to produce partial OF-Config
documents depending on input #capable_switch{} 
record.
Merge branch 'dev'

Conflicts:
	src/of_config_decoder.erl
	src/of_config_encoder.erl
Added hex to binary conversion for decoder.
Merge branch 'dev'

Conflicts:
	test/of_config_tests.erl
Removed default values from OF-Config records.

To support proper encoding of partial configs, 
encoder skips all fields in records that have
value 'undefined'. Thus if we have partially
initialised record it could be properly encoded.