Ember-try doesn't read config location from package.json

[elwayman02]

Developers can specific a custom configPath in the ember-addon section of package.json, but ember-try does not respect this path as the location to find its ember-try.js config file. You can manually override this with the -c flag, but this addon should by default use whatever is specified so that developers don't have to worry about creating workarounds for every tool that has a config file when they need to use a non-default directory location.