Upgrade dependencies and plugins, update README

This release contains no functional changes but is instead focused on project housekeeping.
In addition to project file changes, I also updated the README file:

• Add information about new functions and features.
• Revise code examples to match changes in the underlying API.
• Add notes to clarify the usage of getCallableOf(Description) and encloseCallable(Method, Object, Object...) methods.
• Add note regarding "atomic test" objects supplied with suite-level failures.
• Document new method used to identify retried tests, which handles both @Test and @Theory methods.