Only do gradle check for pull requests

Prior to this commit pull request builds would fail in Travis CI due to missing credentials (for security reasons). This commit limits the builds for the pull requests to the 'check' task to make sure that it builds and that all tests passes.
Merge pull request #375 from bjornerik/travis-pr

Only do gradle check for pull requests
Upgrade to Gradle 1.12
Merge pull request #376 from spring-io/gradle-1.12

Upgrade to Gradle 1.12
Enable the Spring Boot remote shell
Fixes invalid value for ddl-auto

Prior to this commit the property spring.jpa.hibernate.ddl-auto was set to 'false', not a valid value for that property - and a warning was issued by Hibernate. The wanted behaviour is to have "no automatic DDL actions", so the correct is to set it to the (undocumented) value 'none'.
Exclude Commons logging and Log4j from dependencies

Sagan is set up with Logback as the logging framework, with Slf4j bridges from Commons logging, log4j and Java Util logging. Prior to this commit both log4j and Commons logging were included in the dependencies. Commons logging seem to get routed fine to Slf4j, but with libraries using Log4j or JBoss logger (used by Hibernate) it seem to be random due to class loading order (mostly not).

This commit exclude both Log4j and Commons logging from the dependencies.
Revert "Enable the Spring Boot remote shell"

This reverts commit c36fc1a421f17dc487ec11b3f6aaace1ea5f0666 as a
potential remedy for #378.
Merge pull request #373 from bjornerik/logging-cleanup

Exclude Commons logging and Log4j from dependencies
Merge pull request #365 from bjornerik/fix-ddl-auto

Unrecognized property value for spring.jpa.hibernate.ddl-auto