Fix comparison of elapsed time and threshold in SlowRequestFilter

Fixes #423
Fix issue when we specify duration twice.
Upgraded Maven plugins

* maven-enforcer-plugin 1.3.1
* maven-javadoc-plugin 2.9.1
* findbugs-maven-plugin 2.5.3
* maven-shade-plugin 2.2
Upgraded to Hibernate Validator 5.0.2.
Upgraded to Liquibase 3.0.8.
Upgraded to Hibernate 4.3.0.Final.
Upgraded to Mustache 0.8.14.