docs: add koa example since it is in the github title (#1780)
docs: add koa example since it is in the github title (#1780)

* docs: add koa example since it is in the github title

* fix: correct mistake

* Revert "fix: correct mistake"

This reverts commit 1de53f7e2b36c9ac7364a7f291f79bef4f77d777.

* fix: correct mistake

* Update README.md examples.

Follows-up on #1780 by fixing mismatching `port`s in the Koa example and switching other examples to be more DRY with regards to the `port` values.

apollostack/apollo-server