Add NGRX Store for better state management

[zmertens]

Frontend

• Add NGRX store library and use stores in replace of services to manage users and item states
• replace item list view with a table view
• add currency pipe transform to display item prices in the currency specified by Bootstrap drop-down object
• Add total of item costs on list ui

Backend

• Finish item Jest tests
• Add Sendgrid to allow user to reset password via email, and add mock library for user tests