Added new media icons for audio/video

Added icons new icons, deleted an old one.
Using new icons in AudioSlide/VideoSlide.

Closes #2304

res/values/attrs.xml

@@ -51,6 +51,9 @@
     <attr name="conversation_item_sent_push_pending_background" format="reference" />
     <attr name="conversation_item_sent_push_pending_triangle_background" format="reference" />
 
+    <attr name="conversation_icon_attach_audio" format="reference"/>
+    <attr name="conversation_icon_attach_video" format="reference" />
+
     <attr name="contact_selection_push_user" format="reference|color" />
     <attr name="contact_selection_lay_user" format="reference|color" />
     <attr name="contact_selection_label_text" format="reference|color" />

res/values/themes.xml

@@ -94,6 +94,9 @@
         <item name="menu_forward_icon">@drawable/ic_forward_white_24dp</item>
         <item name="menu_save_icon">@drawable/ic_save_white_24dp</item>
 
+        <item name="conversation_icon_attach_audio">@drawable/ic_audio_light</item>
+        <item name="conversation_icon_attach_video">@drawable/ic_video_light</item>
+
         <item name="reminder_header_background">#ff1d85d7</item>
 
         <item name="pref_ic_push">@drawable/ic_push_black</item>
@@ -193,6 +196,9 @@
         <item name="menu_forward_icon">@drawable/ic_forward_white_24dp</item>
         <item name="menu_save_icon">@drawable/ic_save_white_24dp</item>
 
+        <item name="conversation_icon_attach_audio">@drawable/ic_audio_dark</item>
+        <item name="conversation_icon_attach_video">@drawable/ic_video_dark</item>
+
         <item name="reminder_header_background">@color/textsecure_primary_dark</item>
 
         <item name="pref_ic_push">@drawable/ic_push_gray</item>