Delete classes that are deprecated for six years.
Merge pull request #862 from stefanbirkner/remove-deprecated-classes

Delete classes that are deprecated for six years.
remove 'f' prefix from field names, add LEGACY_CODING_STYLE, change CODING_STYLE
Refactor RuleFieldValidator into strategy classes
More precise error message for static MethodRules
Rename RuleFieldValidator to RuleMemberValidator
Allow static @Rule members if also @ClassRule
Merge pull request #932 from rowanhill/non-static-class-rules

Allow members annotated with both @ClassRule and @Rule to be static
Mentions that you need to create a branch
Update CONTRIBUTING.md