Show a link to the MAAS server.

When the provider is MAAS, display a link
to the MAAS management interface in the
header.

Also implemented the EnvironmentGet call
in sandbox mode.
Merge pull request #620 from frankban/maas-server-link

Show a link to the MAAS server.

When the provider is MAAS, display a link
to the MAAS management interface in the
header.

Also implemented the EnvironmentGet call
in sandbox mode.
Add environmnet counts to added services bar.

Specifically, counts for units, services, and machines.