Check for nil creds when trying to load missing netrc

If there's no netrc defined for this api endpoint, output a warning instead of
throwing a shift error
Merge pull request #349 from catsby/warn_netrc_nil

Rescue from NoMethodError when trying to load missing netrc
v2.6.2
Release 2.6.2
Use a relative path for search requests.

The API endpoint for GitHub Enterprise is located at /api/v3. By setting
the preceding / in the api path it's treating the path as a full path
instead of a relative path.
Merge pull request #350 from benburkert/enterprise-search

Use a relative path for search requests