Upgrade to Boot 1.1

This commit updates Sagan to use Spring Boot 1.1.

Sagan's direct use of Flyway has been removed in favour of using the
Flyway auto-configuration that was added in Boot 1.1. To limit the
required configuration the migration scripts have been moved to their
default location.

namingstrategy has been renamed to naming_strategy. While
namingstrategy will work with Boot 1.1 it has been deprecated in
favor of naming_strategy. For consistent use of camel case ddl-auto
has been renamed ddl_auto.

Boot 1.1 now provides auto-configuration for Spring Social. With
spring-social-web on the classpath it will auto-configure a
ConnectController. While Sagan has spring-social-web on its classpath
it does not use a ConnectController, therefore the auto-configuration
has been explicitly excluded.