[Proposal] Reduce build time

[gjrtimmer]

@mattn What do you think about reducing build time on Travis CI ?

Proposal

• Remove Golang:master
• Aggregate several features into a single build GOTAGS command

[mattn]

Yes, it's too long. I prefer second.

[gjrtimmer]

I also would like to suggest we support 2 versions backwards. This would mean the following.

• Golang Current: 1.10.x
• Backwards support 2 versions: Golang:1.9, Golang:1.8 and completly drop 1.7.

@mattn How do you feel about this ?

[mattn]

Sounds good to me. Please do.

[gjrtimmer]

Oke, submitting change to PR #563 and closing this Issue with commit.

[gjrtimmer]

Autoclose on merge of #563