use the minimal supported protocol version in the record layer of the client hello

this helps for interoperability with old servers, and is commonly used by other implementations
style
link to RFC why we choose minimum supported protocol version here
remove out-of-date opam
introduce changes file
rewrite README by using tls-intro.md
add design and attacks from the latest blog post on openmirage.org
fix link
add acknowledgement section
fix syntax
do not validate that no null cipher is proposed by client (breaks on iOS6), fixes #160
Merge pull request #164 from mirleft/version-intolerance

Version intolerance fix
Merge pull request #165 from mirleft/client-handshake-version

Client handshake version
Merge pull request #166 from mirleft/janitor

Janitor
Merge pull request #167 from mirleft/ios6-support

do not validate that no null cipher is proposed by client (breaks on iOS...
reorder ciphers