Add thorough reporting option

[dbarbuzzi]

Add a feature to improve the thoroughness of JUnit reports generated:

• Feature is enabled by setting the NMRE_JUNIT_FULL to 1
• When enabled, it will configure the JUnit reports to include all captured test output (e.g., stdout and stderr channels) as well as include all of this information for passing tests (normally, it is only captured for failing tests)
• When enabled, this does not set any other flags such as to create the report files, that must be done separately either manually or with other features from this plugin

Related changes:

• The README is updated with details about the new feature
• New tests are added/existing tests modified to include coverage for the new feature

[dhuangnm]

LGTM, just a question above.

[andy-neuma]

thanks!