stop conversation list from hogging db

Closes #3883
// FREEBIE

AndroidManifest.xml

@@ -155,7 +155,6 @@
     <activity android:name=".ConversationActivity"
               android:windowSoftInputMode="stateUnchanged"
               android:launchMode="singleTask"
-              android:theme="@style/TextSecure.LightTheme.Popup"
               android:configChanges="touchscreen|keyboard|keyboardHidden|orientation|screenLayout|screenSize" />
 
     <activity android:name=".ConversationPopupActivity"