Upgrade gradle wrapper to 4.4.1

Used command: `./gradlew --no-daemon wrapper --gradle-version 4.4.1 --distribution-type all`

Close #12

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,5 @@
-#Mon Nov 13 15:59:11 GMT 2017
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.4.1-all.zip
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.3.1-all.zip
+zipStoreBase=GRADLE_USER_HOME

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 " "
 }