Feature/link aggr capab junos parser

This patch allows opennaas to parse link aggregation related junos configuration and populate the router model with it.

An aggregator (an interface being the aggregation of several interfaces) is represented in the router model by the AggregatedLogicalPort class.
This class contains the list of interfaces (names) that form the aggregation, together with AggregatedOptions, which is now a place-holder for three options:
- lacpActive
- minimumLinks
- linkSpeed

When junos actionset GetConfigurationAction is executed, the configuration is read and passed to several parsers populating the model. One of these parsers is the IPInterfaceParser, that has been updated in this patch in order to populate the model with link aggregation related classes mentioned above.

This patch fixes issue: http://jira.i2cat.net:8080/browse/OPENNAAS-1365