upgrade koa-compose to 4

[zavr-1]

remove any-promise

[dead-horse]

can you update the node versions in .travis.yml to pass the CI?

[gyson]

koa-compose dependency is only used for convert.compose function at

convert/index.js

Line 29 in 481010e

convert.compose = function (arr) {

I feel that the benefit of convert.compose (a little bit convenience) does not overcome the cost of koa-compose dependency.

Maybe we should remove convert.compose (this is a breaking change and requires koa-convert major version change) and drop koa-compose dependency?

[zavr-1]

please note i've started this issue in koa koajs/koa#1323