Added an Alert text style; Updated rich text editor to reorganize buttons and add text alignment options.

lib/modules/apostrophe-assets/public/css/common.sass

@@ -0,0 +1,17 @@
+.clearfix
+	zoom: 1
+	&:before
+		content: ''
+		display: block
+
+	&:after
+		content: ''
+		display: table
+		clear: both
+.noselect
+	-webkit-touch-callout: none /* iOS Safari */
+	-webkit-user-select: none /* Safari */
+	-khtml-user-select: none /* Konqueror HTML */
+	-moz-user-select: none /* Old versions of Firefox */
+	-ms-user-select: none /* Internet Explorer/Edge */
+	user-select: none /* Non-prefixed version, currently supported by Chrome, Edge, Opera and Firefox */