Added branch coverage

Author: sksamuel

src/main/scala/scales/coverage.scala

@@ -98,7 +98,7 @@ trait CoverageMetrics {
  def statementCount: Int = statements.count(!_.branch)
  def invokedStatements: Iterable[MeasuredStatement] = statements.filter(_.count > 0)
  def invokedStatementCount = invokedStatements.size
- def statementCoverage: Double = invokedStatements / statementCount.toDouble
+ def statementCoverage: Double = invokedStatementCount / statementCount.toDouble
  def statementCoverageFormatted: String = "%.2f".format(statementCoverage * 100)
  def branches: Iterable[MeasuredStatement] = statements.filter(_.branch)
  def branchCount: Int = branches.size