rename default loading animation

...channel-settings/client/stylesheets/channel-settings.less

...s/rocketchat-livechat/app/client/stylesheets/loading.less

packages/rocketchat-livechat/app/client/views/loading.html

...chat-mentions-flextab/client/views/mentionsFlexTab.coffee

...ons-flextab/client/views/stylesheets/mentionsFlexTab.less

packages/rocketchat-theme/assets/stylesheets/base.less

...etchat-theme/assets/stylesheets/utils/_colors.import.less

packages/rocketchat-ui-master/master/loading.html

packages/rocketchat-ui-master/server/inject.js