Preserve leading slash when resolving static paths (#111)

Fixes #101

Author: lihaoyi

cask/src/cask/endpoints/StaticEndpoints.scala

@@ -4,7 +4,8 @@ import cask.router.{HttpEndpoint, Result}
 import cask.model.Request
 object StaticUtil{
   def makePathAndContentType(t: String, ctx: Request) = {
-    val path = (cask.internal.Util.splitPath(t) ++ ctx.remainingPathSegments)
+    val leadingSlash = if (t.startsWith("/")) "/" else ""
+    val path = leadingSlash + (cask.internal.Util.splitPath(t) ++ ctx.remainingPathSegments)
       .filter(s => s != "." && s != "..")
       .mkString("/")
     val contentType = java.nio.file.Files.probeContentType(java.nio.file.Paths.get(path))