Merge branch 'release/0.13' into stable

And one more minor fix to resolve build issues on Buildbot.

gradle.properties

@@ -1,10 +1,13 @@
 # We'd like to enable "configuration on demand" [1] to allow building Themis
 # for Desktop Java without having Android SDK installed, but for some reason
-# it breaks Bintray publishing with a weird error [2]. Keep it disabled.
+# it breaks Bintray publishing with a weird error [2].
+#
+# This option is enabled to keep regular builds working, but you will need
+# to set it to "false" to run "./gradlew :android:bintrayUpload".
 #
 # [1]: https://docs.gradle.org/current/userguide/multi_project_builds.html#sec:configuration_on_demand
 # [2]: https://stackoverflow.com/questions/42552511/cannot-change-dependencies-of-configuration-compile-after-it-has-been-resolve
-org.gradle.configureondemand=false
+org.gradle.configureondemand=true
 
 # Versions of AndroidThemis and JavaThemis packages.
 androidThemisVersion=0.13.0