A client's "contact name" should be "client name"

When creating a client, the user is prompted to give a "contact name", which is then used as "client" in other interfaces. This is confusing and should be known as "client name" everywhere.

Current code also displays the client as "contact name (email)", until the organization field is filled - the client is then displayed as "contact name (organization)". I think this should have a single behaviour: never use the email and display the organization's name when available. I'm not actually convinced that there is really a need to display anything more than the "client name".

Work done in [371769] should eventually make it redundant to have an email address in a client node.