SpringAtom-#25 Create basic viewport

some minor modifications
SpringAtom-#20 Securing the app with Spring-Security

A lot of modifications:
* http-basic (container-based) users authentication
* customized classes used instead of those delivered OOTB by Spring (requirement to have SUser associated with the SPerson instance)
* BCRypt used to manage password encryption/decryption instead of SHA-256
* Session-attack minimized (only one session per user)
* Added SUserService.java that extends from UserDetailsService (Spring) hence makes possible to use SUser
* Modified SSecurityAuthorityEnum.java entries (couldn't have been matched when declared in shortened form - without *ROLE_* prefix)