update icons for mute and unmute

app/static/fonts/icomoon/fonts/icomoon.svg

@@ -11,4 +11,7 @@
 <glyph unicode="&#xe901;" glyph-name="triangle-right" d="M768 460.8l-460.8-256v512l460.8-256z" />
 <glyph unicode="&#xe902;" glyph-name="triangle-left" d="M716.8 716.8v-512l-460.8 256 460.8 256z" />
 <glyph unicode="&#xe903;" glyph-name="triangle-down" d="M256 665.6h512l-256-460.8-256 460.8z" />
+<glyph unicode="&#xe904;" glyph-name="volume_off" d="M512 768.667v-180l-90 90zM182 810.667l714-714-54-54-88 88q-66-56-156-78v88q50 14 96 50l-182 182v-288l-214 214h-170v256h202l-202 202zM810 426.667q0 102-59 180t-153 106v88q130-28 214-133t84-241q0-94-44-178l-64 66q22 54 22 112zM704 426.667q0-18-2-26l-104 104v94q44-22 75-72t31-100z" />
+<glyph unicode="&#xe905;" glyph-name="volume_up" d="M598 800.667q130-28 214-133t84-241-84-241-214-133v88q94 28 153 106t59 180-59 180-153 106v88zM704 426.667q0-120-106-172v344q44-22 75-72t31-100zM128 554.667h170l214 214v-684l-214 214h-170v256z" />
+<glyph unicode="&#xe906;" glyph-name="volume_down" d="M214 554.667h170l214 214v-684l-214 214h-170v256zM790 426.667q0-118-108-172v344q44-22 76-73t32-99z" />
 </font></defs></svg>