(cleanup) Remove regex dependendencies.
Merge pull request #170 from reem/cleanup/remove-unnecessary-regex-dep

(cleanup) Remove regex dependendencies.
(fix) Remove Send bound from Error trait objects.
Merge pull request #173 from reem/fix/no-send-error

(fix) Remove Send bound from Error trait objects.
(refactor) AroundMiddleware produce Handlers instead of being Handlers.
(feat) Show impl for Response.
(feat) Example AroundMiddleware.