Allow conversations to be muted/unmuted

This issue should only be tested in 1 OS. In the app, login in mobilemaster site. Go to messaging and open a conversation. Open the top-right menu. Check that you see an option to mute the conversation (unless you muted it before). Click the mute option. Check that the option becomes "Unmute" and a muted icon appears in the page title (only in phones, not in tablet). Go back to the list of conversations. Check that the conversation displays a muted icon. Perform a PTR in the list of conversations. Check that the conversation still displays a muted icon. Open the conversation again, open the top-right menu and click the unmute option. Check that the option becomes "Mute" and the muted icon disappears from the page title (only in phones, not in tablet). o back to the list of conversations. Check that the conversation no longer displays a muted icon.