fix tomcat version

Author: graemerocher

grails-bootstrap/src/main/groovy/org/codehaus/groovy/grails/resolve/GrailsCoreDependencies.java

@@ -157,7 +157,7 @@ public Object doCall() {
                         registerDependencies(dependencyManager, "docs", docDependencies);
 
                         // dependencies needed during development, but not for deployment
-                        String tomcatVersion = "7.0.30";
+                        String tomcatVersion = "7.0.39";
                         ModuleRevisionId[] providedDependencies = {
                             ModuleRevisionId.newInstance("org.apache.tomcat.embed", "tomcat-embed-core", tomcatVersion),
                             ModuleRevisionId.newInstance("org.apache.tomcat.embed", "tomcat-embed-jasper",tomcatVersion),