Accessible alternatives for radioButtons, checkboxGroupInput and fileInput added

inst/css/a11yShinyInputs.css

@@ -0,0 +1,18 @@
+fieldset.shiny-input-container {
+  
+}
+
+fieldset.shiny-input-container .shiny-options-group div.radio:first-child,
+fieldset.shiny-input-container .shiny-options-group div.checkbox:first-child {
+  margin-top: 0px;
+}
+
+fieldset.shiny-input-container legend {
+  margin-bottom: 5px !important;
+  font-weight: 700 !important;
+}
+
+fieldset.shiny-input-container div.select-all-container {
+  margin-top: -5px;
+  margin-bottom: 10px;
+}