#726 Report JUnit test problems at the end of the build.

• Best to review per commit.
• No end-user visible changes.
• The JUnit tests no long immediately fail the build. Instead, they are collected and reported at the end. I didn't change the documentation/website builds to fail on JUnit test problems, as these skip all tests.
• Other change: Changed names of two build problem collectors. They are now named after entities that have the problems, rather than checker that checks for them.

Addresses #726