add erlang 19, 20 for test

[getong]

No description provided.

[massemanet]

thanks for the pr.
will have to fix the failures before merge

[getong]

=INFO REPORT==== 29-Aug-2017::07:41:28 ===
    current_function: {prfHost,loop,1}
    line: 119
    lost_target: {killed,{gen_server,call,[prfDog,quit]}}

=INFO REPORT==== 29-Aug-2017::07:41:28 ===
    current_function: {watchdog,mk_send_tcp,4}
    line: 541
    {didnt_make_subscriber,tcp,{badmatch,{error,econnrefused}}}

Pending:
  prfDog:t1_test/0
    %% Unknown error: timeout
  undefined
    %% Unknown error: {blame,[1,1,19,2]}

I ran three times, and the first time faild. The other two work.

[hanssv]

Fixing make test to do dialyzer rather than dialyze will probably reveal more problems...

[massemanet]

typos... they're so amusing :<
alas, dialyzing redbug is doomed since OTP added a bunch of bogus optimistic type annotations to the parser. There might be are probably legit errors, but since I've moved redbug development to http://github.com/massemanet/redbug I'm not going to fix them.