remove unused resources

briar-android/res/drawable/ic_chat.xml

briar-android/res/drawable/ic_expand_more_black_24dp.xml

briar-android/res/layout/activity_blog.xml

briar-android/res/layout/dropdown_author.xml

briar-android/res/layout/fragment_blogs.xml

briar-android/res/layout/fragment_blogs_my.xml

briar-android/res/menu/blogs_my_actions.xml

briar-android/res/values/color.xml

briar-android/res/values/dimens.xml

briar-android/res/values/strings.xml