Add 'back' button

app/assets/stylesheets/components/button.scss

@@ -0,0 +1,10 @@
+.button {
+
+  &-secondary {
+    @include button($grey-1);
+    padding: 0.52632em 0.78947em 0.26316em 0.78947em;
+    @include inline-block;
+    margin-left: 5px;
+  }
+
+}

app/assets/stylesheets/main.scss

@@ -30,6 +30,7 @@
 @import "components/sms-message";
 @import "components/placeholder";
 @import "components/template-picker";
+@import "components/button";
 @import "components/table";
 
 // TODO: break this up into components

app/templates/views/check-sms.html

@@ -20,6 +20,7 @@
 				<form method="POST" enctype="multipart/form-data">
 					<input type="hidden" name="csrf_token" value="{{ csrf_token() }}" />
 			  	<input type="submit" class="button" value="Send {{recipients|length}} text messages" />
+					<a class="button-secondary" role="button" href="{{ url_for(".sendsms") }}">Back</a>
 				</form>
 	  	</p>
 		</div>