Initial support for native protocol v2

No new features added.
Add v2 authentication request/response messages
Support for query parameters (e.g. paging, serial consistency)
Add support for BATCH request
Some irrelevant changes
Add support for batch request

Right now it only supports prepared queries.
Bump to 0.2.0-pre1.
Return name and query when erlcql_client:prepare/3 fails

Fixes #26
Merge pull request #28 from puzza007/gh-26-prepared-query-errors

Return name and query when erlcql_client:prepare/3 fails
Don't test with R14 on Travis
Add default_timeout config option
Merge pull request #30 from puzza007/default-timeout-config-option

Add default_timeout config option
Only return stream id when the response gets to the right caller

WIP.
Only return stream when we get a response on it
vsn 0.2.1
Merge pull request #1 from Regulators/fix-timeout-bug

Fix timeout bug
Add metrics
Lager is the default, always
Tweak Makefile
Pin to lager 2.0.3
Use quintana