Use wiredep for sass and less injection

https://github.com/taptapship/wiredep
all third-party deps are injected via wiredep rather than manually managed

assets/styles/main.less

@@ -1,5 +1,6 @@
-// Bootstrap
-@import "_bootstrap";
+// bower:less
+@import "../../bower_components/bootstrap/less/bootstrap.less";
+// endbower
 
 // Variable overrides and custom variables
 @import "_variables";