Added verbose error message for a wrong status

If the server returns a 404 error message for the api url then the code will break when a subsequent method tries to analyse that response body. This way the error is clearer.
Fixed timeout that happened if an error occurs

When an error occurred it will just log the error but not return anything. FIxed that by just returning the error.
Merge pull request #5 from martinheidegger/patch-3

Fixed timeout that happened if an error occurs
Merge pull request #4 from martinheidegger/patch-2

Added verbose error message for a wrong status
Rebased
Merge branch 'patch-1' of github.com:martinheidegger/strider-gitlab into patch-1

Conflicts:
	lib/api.js