Expose MySQL columns

Expose some MySQL info

- Expose connection status.
- Expose columns/fields for prepared statements.
- Add support for connection reset.

Release v1.5.0 (go-sql-driver#1047)

* CHANGELOG: include v1.4.1

* Release v1.5.0

Release v1.4.1

Release v1.4.0 (go-sql-driver#809)

Version 1.3.0

Release v1.3 (go-sql-driver#517)

* Update CHANGELOG
* README: Removed most recent version and build status

Version 1.2.0

Release v1.2

Version 1.1.0