Add Eyeglass operation made functional.

Users can now add an eyeglass to the database, which includes Sku calculation and DateAdded assignment.

Things to do to make this operation user-friendly and complete:
1) Feedback - user needs to know that the Add completed and ESPECIALLY what the assigned Sku is.  Probably should be a summary pane in a partial view, AJAX preferred.  Also clear the form for the next entry.

2) Client-side validation and autocomplete: immediate feedback of incorrect Rx values, also autocomplete the decimal values (e.g. user types 1.2<tab> and autocomplete makes it 1.25).

3) Incorporate AddedByUserId.  This will happen when the account management system is ready.