Added autoGitTag to github and bintray configurations.

modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/misc/Git.kt

@@ -0,0 +1,43 @@
+package com.beust.kobalt.misc
+
+import com.beust.kobalt.TaskResult
+import com.beust.kobalt.api.Project
+import com.google.inject.Inject
+import java.io.File
+
+class Git @Inject constructor() {
+    fun maybeTagRelease(project: Project, uploadResult: TaskResult, autoGitTag: Boolean) : TaskResult {
+        val result =
+                if (uploadResult.success && autoGitTag) {
+                    val tagSuccess = tagRelease(project)
+                    if (! tagSuccess) {
+                        TaskResult(false, "Couldn't tag the project")
+                    } else {
+                        TaskResult()
+                    }
+                } else {
+                    TaskResult()
+                }
+        return result
+    }
+
+    private fun tagRelease(project: Project) : Boolean {
+        val success = try {
+            log(2, "Tagging this release as \"${project.version}\"")
+            val repo = org.eclipse.jgit.storage.file.FileRepositoryBuilder()
+                    .setGitDir(File(KFiles.joinDir(project.directory, ".git")))
+                    .readEnvironment()
+                    .findGitDir()
+                    .build()
+            val git = org.eclipse.jgit.api.Git(repo)
+            val ref = git.tag().setName(project.version).call()
+            git.push().setPushTags().call()
+            true
+        } catch(ex: Exception) {
+            warn("Couldn't create tag ${project.version}: ${ex.message}", ex)
+            false
+        }
+
+        return success
+    }
+}