Account should retrieve it's organization from the memberships default organization.

Add support to MembershipsSet collection for getting and setting the default membership.
Return all accounts that have organizations in common

This will be used by the workspace in order to populate the sidebar
with all the organizations the logged in account belongs to
New Account#organizations_with_accounts method.

Adds a new method to accounts which returns an array of all the
membership's canonical data, including the memberships and accounts.

The data is used in the workspace to populate the Organizations sidebar.