get-components-by-dir issue

[mattiaerre]

Description

after the release v0.36.16, if you try to run oc dev . where there is a folder w/ a package.json file in it and this folder doesn't contain a component, you get the following error:

Cannot read property 'files' of undefined

this is because the function isOcComponent returns true also if the oc section is missing in the package.json.

I believe that the problem has been introduced w/ this PR:

#447

and in particular:

https://github.com/opentable/oc/pull/447/files#diff-6810304ebc65ef9905ca3d7d77d8a311

[mattiaerre]

I am going to create a PR for this