refs #6038 make it possible again to change the used font. The font was always...

refs #6038 make it possible again to change the used font. The font was always overwritten by Morpheus so it has to be in an imported file now. Need to update the guides...

plugins/ExampleTheme/stylesheets/_variables.less

+@theme-fontFamily-base: Verdana, sans-serif;

plugins/ExampleTheme/stylesheets/theme.less

 @import "_colors.less";
-
-@theme-fontFamily-base: Verdana, sans-serif;
-
+@import "_variables.less";