Reviewer invitation fixes

This restores the reviewer functionality that was broken by the
account<->memberships split.
Request additional information after a social login.

When the user login originates from omniauth using third party
authentication, show the user what their first and last name will be
displayed as and give them an option to update it.

Still needs additional checks on the account to determine whether or
not to run the account validations, and the input form needs
instructions.
Export listing of an accounts memberships to workspace

This sets up a new backbone model/collection for Memberships.  A
memberships attribute is then set on dc.account containing the current
list of memberships the account belongs to.
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.
Rewrite Account#organizations_with_accounts

Construct our own json instead of using canonical.  SQL query runs
much faster without querying organization info for each nested account
Rewrite Account#organizations_with_accounts to SQL

Not happy with this trade-off.  Is only marginally more efficient.
New & Improved interface for populating an account's organizations members
Restrict to 'real' roles and allow removing a given account from
organizations members.
Modify backbone data model to be multi organization aware

Account's can have multiple organizations and each organization can have multiple members
Return slug along with organization#members
UI for multiple organizations appearing in sidebar

This displays a listing of all the organizations an account belongs to
in the sidebar with toggle support for showing the other members that
belong to the organization
Merge branch 'memberships' of github.com:nathanstitt/documentcloud into memberships

Conflicts:
	app/controllers/workspace_controller.rb
	app/views/accounts/_current_account.js.erb
Merge branch 'memberships-ensure-name' into memberships
Merge branch 'memberships-reviewers' into memberships
Merge branch 'memberships-workspace' into memberships.  Fixup a few merge conflicts, choose upstream when possible

Conflicts:
	app/controllers/workspace_controller.rb
	app/models/organization.rb
	app/views/accounts/_current_account.js.erb