suppress test classes that are in a "tests" folder

[tusharnarayan]

for example, integration tests that live in src/integrationTests/java

noticed because after #240, static imports in classes within my integrationTests folder were causing checkstyle violations - figured we want to make the s optional for test all suppression rules

[tusharnarayan]

@uschi2000 and @iamdanfox for review

[iamdanfox]

@tusharnarayan would you consider renaming your source set to integrationTest for consistency with the existing singular test one? It seems kinda preferrable to unify on singular names rather than supporting both singular and plural?

[tusharnarayan]

yeah i poked around a couple projects first, seems like a number of folks are using integrationTests - i'm down to rename if that's something we want to standardize on

[iamdanfox]

Cool, I think it makes sense to just match the existing singular noun approach and use src, test, integrationTest/integTest and ete rather than plurals