Override toString() in all RequestMatcher implementations

[wilkinsona]

It would improve Spring Security's diagnostics and make debugging a little easier if all RequestMatcher implementations overrode toString(). Based on find . -name "*RequestMatcher.java" | xargs grep -L 'String toString()', the following do not currently do so:

• MvcRequestMatcher
• AnyRequestMatcher
• ELRequestMatcher
• RegexRequestMatcher

[rwinch]

Thanks for the report @wilkinsona! The changes are now pushed to master