add freemarker (for email usage)

build.gradle

@@ -55,6 +55,8 @@ dependencies {
 	implementation group: 'io.jsonwebtoken', name: 'jjwt-impl', version: '0.11.5'
 	implementation group: 'io.jsonwebtoken', name: 'jjwt-jackson', version: '0.11.5'
 
+	implementation group: 'org.freemarker', name: 'freemarker', version: '2.3.32'
+
 	implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
 	implementation "org.jetbrains.kotlin:kotlin-reflect"