Inspections to offer builtin matchers in specs2.

Before:

class TestSpec extends Specification { def is = s2"""
  This is a spec
  opt
    should contain 1                                  $e1
                                                      """
  def e1 = {

    val opt = Some(1)

    opt must equalTo (Some(1))
  }
}

After:

class TestSpec extends Specification { def is = s2"""
  This is a spec
  opt
    should contain 1                                  $e1
                                                      """
  def e1 = {

    val opt = Some(1)

    opt must beSome(1)
  }
}