Refactor key struct and add GetClientKey method#51

ar4s wants to merge 1 commit intoatlassian:masteratlassian/go-sentry-api:masterfrom

ar4s:feat/keys--add-name-and-retrive-key-by-idar4s/go-sentry-api:feat/keys--add-name-and-retrive-key-by-idCopy head branch name to clipboard