Add ExpectPing() to Sqlmock interface

[dhui]

I noticed that #68 mentions that there's no ExpectPing() since it's not backwards compatible.

Can ExpectPing() be added now that Go 1.9 (soon to be Go 1.10) is the oldest supported release?

[l3pp4rd]

Hi, likely will need to revisit this.

[Melaninneal]

Bumping this

[dhui]

Looks like this is fixed by #204

[dhui]

Any chance of cutting a new release soon? The master branch seems to work fine for my usage.

[l3pp4rd]

done