Factored out StartWithWord.


git-svn-id: http://scalatest.googlecode.com/svn/trunk@5065 fd1274fd-080f-5963-8033-43ee40fcd1de
Factored EndWithWord and IncludeWord out of Matchers.scala.


git-svn-id: http://scalatest.googlecode.com/svn/trunk@5066 fd1274fd-080f-5963-8033-43ee40fcd1de