Upgrade to Gradle 4.5.1

Closes gh-589

initializr-generator/src/main/resources/project/gradle4/gradlew

@@ -33,11 +33,11 @@ DEFAULT_JVM_OPTS=""
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"
 
-warn () {
+warn ( ) {
     echo "$*"
 }
 
-die () {
+die ( ) {
     echo
     echo "$*"
     echo
@@ -155,7 +155,7 @@ if $cygwin ; then
 fi
 
 # Escape application args
-save () {
+save ( ) {
     for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
     echo " "
 }