fix(stylus): remove bootstrap css import in stylus when bootstrap is not selected

Closes #368

Author: DaftMonk

app/templates/client/app/app(stylus).styl

@@ -1,5 +1,5 @@
-@import "bootstrap/dist/css/bootstrap.css"
 @import "font-awesome/css/font-awesome.css"
+<% if(filters.bootstrap) { %>@import "bootstrap/dist/css/bootstrap.css"
 
 //
 // Bootstrap Fonts
@@ -12,7 +12,7 @@
     url('../bower_components/bootstrap/fonts/glyphicons-halflings-regular.woff') format('woff'),
     url('../bower_components/bootstrap/fonts/glyphicons-halflings-regular.ttf') format('truetype'),
     url('../bower_components/bootstrap/fonts/glyphicons-halflings-regular.svg#glyphicons_halflingsregular') format('svg');
-
+<% } %>
 //
 // Font Awesome Fonts
 //