Bump version to 2.6.4

// FREEBIE

Author: moxie0

AndroidManifest.xml

@@ -2,8 +2,8 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
           xmlns:tools="http://schemas.android.com/tools"
           package="org.thoughtcrime.securesms"
-      android:versionCode="98"
-      android:versionName="2.6.3">
+      android:versionCode="99"
+      android:versionName="2.6.4">
 
     <permission android:name="org.thoughtcrime.securesms.ACCESS_SECRETS"
                 android:label="Access to TextSecure Secrets"