Repobee-junit4

This is a very minor release that updates repobee-junit4 to be compatible with RepoBee v2.4.0. It does not affect usage in any way.

Documentation
* 6b95c2f Fix typo (70)

Refactorings
* 631b939 Adapt to repobee-plug 0.12.0, fix 71
- This makes it compatible with RepoBee v2.4.0

Hotfix for a typo in test result output, refer to the [v0.8.0 release notes](https://github.com/repobee/repobee-junit4/releases/tag/v0.8.0) for more information on version 0.8.x.

Features
* 98c6b9d Add `--junit4-timeout` option to specify a hard time limit for tests (69)
* 5e895ac Tweak verbosity levels of compile error output (66)
* 70f73e5 Completely redesign test output (63)
* 4d46a5a Check that specified jars actually exist (61)
Bugfixes
* 255e555 Add -enableassertions flag to java command (67)
Documentation
* 9760324 Document the --junit4-timeout option
* 0d885e9 Add _output module to documentation
Refactorings
* 6098eb5 Prefix CLI option destinations with "junit4_", fix 68
Other
* b2b38b5 Tweak test summary message
* b236c6e Add Python 3.8 to Travis config, fix 60

Changelog
Features
* c2dfe57 Add option to run student test classes instead of reference tests (57)
* 4cf235f Prefix cli options with --junit4 (56)
- **Breaking change!**
Bugfixes
* d56e66c Convert mid-execution errors into hook result (51)
- Instead of crashing mid-execution, an error is reported for that repo after all hooks have run
Documentation
* f7e36f7 Add a short description of the plugin to the index page
* e5964e6 Revert the status of the plugin from beta to alpha
* 586ffc8 Update documentation for v0.7.0, fix 55

Features
* dcac014 Crash immediately when reference tests dir does not exist (48)

Other
* 0a5ab91 Make compatible with repobee-plug v0.9.0 (49)

Changelog
* 5414f8b3788bfe18d4a7913cea7e51dc2c592484 `repomate-junit4` is now `repobee-junit4`