Merge pull request #43 from asadoughi/put_to_post_ports

Moved implementation of PUT /ports to POST /ports
Merge pull request #51 from asadoughi/update_subnet_squash

Implemented additional subnet attributes
Merge pull request #54 from asadoughi/extensions_coverage

Added coverage for api_extensions_path configuration
Merge remote-tracking branch 'jkoelker/master' into update_ports