update fixtures/package.json to test 'directories' and 'bin' fields

The plugin should add link to 'bin' field and distinguish the bin/main
directory in 'directories' field from 'bin' field and 'main' field
add links to 'directories' field of package.json.

By this way, we also change the html structure of 'directories' field,
make it possible to distinguish 'main' and 'bin' fields from those in
'directories'
add link to 'bin' field of package.json
Merge branch 'master' of github.com:stefanbuck/github-linker-core

* 'master' of github.com:stefanbuck/github-linker-core:
  add links to 'directories' field of package.json and 'bin' field
add missing remote tests