Set version to rc1 and also update kotlin version

This CL also adds a bintray plugin to easily upload artifacts to bintray.
The plugin is a separate project (because main project depends on it) so
I've committed it as a prebuilt since it is unlikely to change.

Change-Id: I801b334e40bfb49a18bf7190e5100e0910a606a2
diff --git a/build.gradle b/build.gradle
index da2f10e..01e3c42 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,6 +2,7 @@
 databindingProperties.load(new FileInputStream("${projectDir}/databinding.properties"))
 def repoBase = databindingProperties.mavenRepoAbsolutePath == "." ? projectDir : databindingProperties.mavenRepoAbsolutePath
 databindingProperties.mavenRepoDir = "${repoBase}/${databindingProperties.mavenRepoName}"
+databindingProperties.extraPluginsRepoDir = "${projectDir}/${databindingProperties.extraPluginsRepoName}"
 
 databindingProperties.eapOutDir = "${projectDir}/${databindingProperties.eapOutFolderName}"
 databindingProperties.prebuildFolder = "${projectDir}/${databindingProperties.prebuildFolderName}" +
@@ -18,6 +19,17 @@
     apply plugin: 'maven'
     group = config.group
     version = config.version
+    buildscript {
+        repositories {
+            maven {
+                url "file://${config.extraPluginsRepoDir}"
+            }
+        }
+        dependencies {
+            classpath "com.android.databinding:bintray:${config.extraPluginsVersion}"
+        }
+    }
+
     repositories {
         mavenCentral()
         maven {
@@ -33,7 +45,6 @@
     }
 }
 
-
 task deleteRepo(type: Delete) {
     delete "${config.mavenRepoDir}/${config.group.replace('.', '/')}"
 }