I have the following dependency in my pom.xml so that my IDE (IntelliJ) has the servlet-api classes available during compilation, but not provided in the build.
I use the following sbt project setting to fix a similar problem:
"any dependency program that includes servlet-api java library code" % excludeAll ExclusionRule(organization = "org.eclipse.jetty.servlet-api"), "org.mortbay.jetty" % "servlet-api" % "3.0.20100224"