Remove unused imports

Initial step for #14
Add regex to validate email address

Hibernate's @Email will accept address such as 'user@domain'. This however is not a valid email address. Add another regex which supports standard email address format.

Fixes #14
Add ControllerAdvice to massage errors being sent to client

Default error message that being sent to client is difficult to read. It contains to much unnecessary information. Remove those information and only return relevant information to avoid difficulty for clients to understand.

Fixes #14
Add tests to validate data being sent by client

Add tests to ensure that all required information is provided. Also validate that email format is correct.

Fixed #14
Bump to version 1.1.1-SNAPSHOT
Remove dependencies on spring-boot-starter-tomcat and json-path

spring-boot-starter-tomcat was never being used in the first place. It was there due to assumption that it might be needed.

json-path is no longer needed since the implementation for UserControllerTest has changed.

Fixes #15
Remove templates directory

The directory was there to satisfy the need of IndexController which will direct to index.html. However now it has been turned into a rest service the folder is unnecessary.

Fixed #15
Add dependency to spring-boot-starter-data-rest

spring-boot-starter-data-rest is needed to allow the usage of
@RepositoryRestResource

gh-16
Add example for @RepositoryRestResource

Introduce new table "quote" along with sample data and QuoteRepository
to demonstrate the usage of @RepositoryRestResource.