Added manifest in the release jar file.

Prepare to publish on jCenter.
Related to #351

build.gradle

@@ -59,6 +59,20 @@ dependencies {
 }
 
 jar {
+    manifest {
+        attributes 'Built-By': 'Electrical-Age Team'
+        attributes 'Build-Date': new Date().format("yyyy-MM-dd HH:mm:ss")
+        attributes 'Built-JDK': System.getProperty('java.version')
+        attributes 'Implementation-Title': project.name
+        attributes 'Implementation-URL': 'https://github.com/Electrical-Age'
+        attributes 'Implementation-Vendor': 'Electrical-Age Team'
+        attributes 'Implementation-Vendor-Id': 'net.electricalage.eln'
+        attributes 'Implementation-Version': project.version
+        attributes 'Project-Url': 'https://electrical-age.net/'
+        attributes 'Source-Compatibility': project.sourceCompatibility
+        attributes 'Target-Compatibility': project.targetCompatibility
+    }
+
     from { configurations.external.collect { it.isDirectory() ? it : zipTree(it) } }
     exclude(['dan200/**', 'ic2/**', 'li/**', 'buildcraft/**'])
 

gradle.properties

@@ -1,4 +1,4 @@
-GROUP=com.Miaou.Eln
-ARCHIVE_NAME=ElectricalAge_BETA
-VERSION=1.9_r51
-MAP_URL=https://github.com/Dolu1990/ElectricalAge/releases/download/BETA-1.9/ElectricalAge_tutorialMap_BETA-1.9_r41.zip
+GROUP = 'net.electricalage.eln'
+ARCHIVE_NAME = 'ElectricalAge_BETA'
+VERSION = '1.9_r51'
+MAPURL = 'https://github.com/Dolu1990/ElectricalAge/releases/download/BETA-1.9/ElectricalAge_tutorialMap_BETA-1.9_r41.zip'