Remove SBT build files.

Maven is the main way to build the project, let's avoid confusion.

Closes #184.

build.sbt

@@ -1,17 +0,0 @@
-seq(samskivert.POMUtil.pomToSettings("pom.xml") :_*)
-
-crossPaths := false
-
-javacOptions ++= Seq(
-  "-Xlint", "-Xlint:-serial", "-source", "1.6", "-target", "1.6"
-)
-
-autoScalaLibrary := false // no scala-library dependency
-
-libraryDependencies += "com.novocode" % "junit-interface" % "0.7" % "test->default"
-
-// filter the super-source directory from the build
-unmanagedSources in Compile ~= (_.filterNot(_.getPath.indexOf("com/samskivert/gwt") != -1))
-
-// add our sources to the main jar file (including super-sources)
-unmanagedResourceDirectories in Compile <+= baseDirectory / "src/main/java"

project/plugins.sbt

@@ -1 +0,0 @@
-libraryDependencies += "com.samskivert" % "sbt-pom-util" % "0.6"