maas: static-ipaddresses capability detection
Merge pull request #925 from dimitern/maas-provider-static-ipaddresses-cap

maas: static-ipaddresses capability detection

Now the environment capability SupportsAddressAllocation
actually uses the MAAS version API to check if the needed
"static-ipaddresses" capability is supported. Bumped the
gomaasapi revision in dependencies.tsv.