Build Failure Analyzer integration: show number of detected failures

The build monitor can show failures detected by the Build Failure
Analyzer plugin, with output like:
    Identified problems: foo, bar, baz

This commit adds the number of detected failures, as follows:
    Identified problems (3): foo, bar, baz

This commit is similar to pull request #28, but leverages the existing integration with the Build Failure Analyzer plugin, which supports recognition of JUnit test results since version 1.11.0.