Fix client verification and wording

Per https://github.com/bitly/go-nsq/commit/5429f88b67f4593dba706e84dd7631004ea2714a#commitcomment-7481700,
"When the tls.Config is used for a TLS client, it should be setting c.TlsConfig.RootCAs,
not .ClientCAs; otherwise there will be no possible roots to verify the server cert."

Because go-nsq is always used as a client, RootCAs needs to be set, not ClientCAs.

Lastly, the cert is public, not private, and the key is private, not public.
Merge pull request #77 from twmb/fix_tls

Fix client verification and wording
bump v1.0.1-alpha
config: fix tls_cert tls_key handling
refactor tests and add additional TLS tests
Merge pull request #78 from mreiferson/tls_fixes_78

TLS is (I believe) broken
drop go10 compatibility
Merge pull request #79 from mreiferson/drop_go10_79

drop go1.0 compatibility
producer: fix panic when conn is never assigned
Merge pull request #82 from mreiferson/producer_panic_82

producer: panic on error before first connection
config: document tls_v1
Merge pull request #81 from mreiferson/tls_updates_81

auto enable TLS negotation when setting other TLS options
consumer: send RDY before FIN/REQ
Merge pull request #83 from mreiferson/backoff_rdy_83

consumer: send RDY before FIN/REQ
add LICENSE
pluggable "behavior delegate", currently just for DiscoveryFilter

for modifying nsq consumer behavior at some defined points
panic()s if the behavior delegate casts to no known interfaces

currently just supports DiscoveryFilter (with a Filter() method),
to filter the nsqd addresses resulting from discovery (via nsqlookupd)
Merge pull request #86 from ploxiln/pluggable_lookup_provider_86

make lookup functionality pluggable
config: allow heartbeat_interval and output_buffer_timeout to be disabled
Merge pull request #87 from mreiferson/fix_disable_identify_87

Config doesn't accept -1 for output_buffer_timeout
consumer: fix discovery behavior delegate