language: go
install: make deps
go:
  - 1.4
  - tip

language: go
install: make deps
go:
  - 1.4
  - 1.5
  - 1.6
  - tip

Add Go 1.5 and 1.6 to build matrix.
Add Go 1.5 and 1.6 to build matrix.

I've left 1.4 in the build matrix as some users may still be using it
because of the regression in build times of 1.5 and 1.6.
