Move definition of MessageSource bean to ApplicationContext.

No functional changes.
Move SecurityConfig to its own special package.

No functional changes.
Implemented sending of mail with activation key.

Also added support for feature flags. You can enable/disable them in runtime by opening /togglz URL
under admin account.

Fixed #64 (GH #1)
site/index: started to porting
simplify th:text
site/index: connect Spring Security and finish page porting.
site/index: improve presentation view.
Connected tiles.
site/index: remove jsp
deal with links
jsp2thymeleaf: added
site/index: fix i18n.
fixed markup
account/auth: started porting.
fixed re-displaying of login.
account/auth: use th:with
account/auth: fixed error
account/register: ported.
account/auth.jsp: removed.
account/activate: ported.