Testing and QA

I've updated the page, the changes are:

1. new text for the MySQL collation issues: "This is expected to fail if you are running MySQL. These tests should pass if you use the utf8_bin collation on your database for unit tests, but we recommend utf8_unicode_ci for actual live Moodle sites. Work is being done to resolve this issue, read more about the Database collation issue for further info."

2. grouping the three MySQL failures together

3. changing the solutions from being seperate headings as it was cluttering the table of contents

4. making command line error messages, or instructions of what to type to fix problems into code rather than quoted text.

5. seperating out general issues (like the tests taking too long) from specific individual failures.

I also filed a bug for adding a pointer to this page from the releveant unit test failure messages: MDL-43132