workaround dexmaker bug in test cases

// FREEBIE

androidTest/java/org/thoughtcrime/securesms/TextSecureTestCase.java

@@ -0,0 +1,16 @@
+package org.thoughtcrime.securesms;
+
+import android.content.Context;
+import android.test.InstrumentationTestCase;
+
+public class TextSecureTestCase extends InstrumentationTestCase {
+
+  @Override
+  public void setUp() throws Exception {
+    System.setProperty("dexmaker.dexcache", getInstrumentation().getTargetContext().getCacheDir().getPath());
+  }
+
+  protected Context getContext() {
+    return getInstrumentation().getContext();
+  }
+}