Remove :versions prefix from gradle projects and remove duplicated build code

versions/core/.gitignore

@@ -0,0 +1 @@
+mcVersion

versions/core/build.gradle

@@ -1,69 +0,0 @@
-buildscript {
-    dependencies {
-        //#if MC>=10904
-        //#if MC>=11200
-        classpath 'net.minecraftforge.gradle:ForgeGradle:2.3-SNAPSHOT'
-        //#else
-        //$$ classpath 'net.minecraftforge.gradle:ForgeGradle:2.2-SNAPSHOT'
-        //#endif
-        //#else
-        //#if MC>=10809
-        //$$ classpath 'net.minecraftforge.gradle:ForgeGradle:2.1-SNAPSHOT'
-        //#else
-        //$$ classpath 'net.minecraftforge.gradle:ForgeGradle:2.0-SNAPSHOT'
-        //#endif
-        //#endif
-    }
-}
-
-apply from: '../common.gradle'
-
-sourceSets {
-    main.java.srcDirs = ['../../src/main/java']
-    main.resources.srcDirs = ['../../src/main/resources']
-}
-
-minecraft {
-    //#if MC>=11202
-    version = '1.12.2-14.23.0.2486'
-    mappings = "snapshot_20170615"
-    //#else
-    //#if MC>=11201
-    //$$ version = '1.12.1-14.22.0.2444'
-    //$$ mappings = "snapshot_20170615"
-    //#else
-    //#if MC>=11200
-    //$$ version = '1.12-14.21.1.2387'
-    //$$ mappings = "snapshot_20170615"
-    //#else
-    //#if MC>=11102
-    //$$ version = '1.11.2-13.20.0.2216'
-    //$$ mappings = "snapshot_20161220"
-    //#else
-    //#if MC>=11100
-    //$$ version = '1.11-13.19.1.2188'
-    //$$ mappings = "snapshot_20161111"
-    //#else
-    //#if MC>=11002
-    //$$ version = '1.10.2-12.18.2.2099'
-    //$$ mappings = "snapshot_20160518"
-    //#else
-    //#if MC>=10904
-    //$$ version = '1.9.4-12.17.0.1976'
-    //$$ mappings = "snapshot_20160518"
-    //#else
-    //#if MC>=10809
-    //$$ version = '1.8.9-11.15.1.1722'
-    //$$ mappings = "stable_22"
-    //#else
-    //$$ version = '1.8-11.14.4.1563'
-    //$$ mappings = "snapshot_nodoc_20141130"
-    //#endif
-    //#endif
-    //#endif
-    //#endif
-    //#endif
-    //#endif
-    //#endif
-    //#endif
-}