[L3D] list pools by layer3domain

[1and1]

[L3D] list pools by layer3domain

[zeromind]

During specification I seem to have missed something like

ndcli list pools [VLANID|CIDR|POOL] [layer3domain l3d]

Unfortunately it's not easily possible to have that order due to the nature of the query (VLANID|CIDR|POOL), which supports 3 different types without a keyword. layer3domain would be mistaken as POOL.

I've implemented it in the other way around (#193), which matches what's available for ndcli list containers:

Usage: ndcli list pools [layer3domain LAYER3DOMAIN] [VLANID|CIDR|POOL]

 Displays the list of matching pools.

If no query parameter is given, all the pools are selected. Otherwise, the
parameter is tested to determine its type in the following order:

* VLAN_ID: positive integer >=2 and <=4094
* CIDR: address/prefix
* POOL: any string. You may use '*' for matching multiple characters and '?' for
  matching single characters.

Usage: ndcli list containers [layer3domain LAYER3DOMAIN] [CONTAINER]

 list the children of a container