During the oauth dance two tokens pairs are generated and saved into a session; getAccessToken() passes the most recent token/token_secret pair to the callback function. This couple is the actual access token that needs to be saved in the current session and has to be used to sign futher requests. See: https://developer.linkedin.com/documents/getting-oauth-token
with parametrized paths (commit 76c2109).
Some API methods requires the first parameter to be appended with and '?' char. When one or more parameters are added to a path (eg. /people-search?keywords=), prepend a '&' char to the hardcoded 'format=json' string.