Switch Travis to JDK12

Switch to SecureRandom() instead of getStrongInstance() to avoid
blocking hideously.

Closes #16

If we're keeping some bytes in the line buffer waiting for a
CR/LF, the SSLEngine may not have enough room to put a packet's
worth of data in.

Instead of managing a single buffer, keep a channel of them
and emit a complete buffer each read call.

Closes #14

If we multiple long lines in succession the start index got
miscalculated and part of the latter lines discarded.

Move message processors into their own package
Update ktor

Closes #11

Move handlers to their own packages
Update JUnit

Fix regression with capability negotiation

To preserve the order of lines we offer them into a channel
without suspending. If we launch a new coroutine there's no
guarantee they'll execute in order, even if the method they
call is fair.

Expose status (connecting, negotiating, ready)
Fire ServerReady and ServerConnected events