supply proper links for the badges
allow for non-existing data bag `users
simplify tests: remove unneeded dummy data bags
merge identical contextes in server spec
reword misleading test description
Merge pull request #48 from bkw/badges

supply proper links for the badges
Merge pull request #50 from bkw/databagOptional

make users data bag optional
split weak_* attributes into client and server ones
add tests for new weak_ attribs and transition logic
update docs about split of cbc_required, weak_hmac and weak_kex