Unable to find apiKey.properties file when ~ is used

[typerandom]

Fixes a issue where an API key wouldn't be loaded correctly from a home path.

How to reproduce

1. Checkout the stormpath-config master branch.
2. Execute $ npm link to make it available as a link.
3. Create an empty test project folder (e.g. stormpath-config-test) and $ cd into it.
4. Execute $ npm init --yes.
5. Execute $ npm link stormpath-config so that we link to our stormpath-config master branch.
6. Create a new file called app.js and put the contents of this gist in it.
7. Create an apiKey.properties with the following content and put it in the ~/.stormpath/ directory.
8. Run $ node app.js.

Actual

Console outputs:

[Error: Client API key file not found: /Users/orhedenr/.stormpath/apiKey.properties] undefined

Expected

Console outputs:

null { bob: 123, client: { apiKey: { id: 'abc', secret: 'def' } } }