Add request helper

This will handle settings things such as strict SSL or proxy settings
that should be loaded from the npm config files
Use request helper in View class
Use request helper in Develop class
Remove unused require
Use request helper in Featured class
Remove unused require
Use request helper in Publish class
Use request helper in Search class
Use request helper in ThemeConverter class
Use request helper in Unpublish class
Use request helper from Upgrade class
Add post helper
Use request helper in Install class
Use request helper in PackageConverter class
Use fat arrow for stream callback
Mention ~/.atom/.apmrc file
Merge pull request #114 from atom/ks-ssl-settings

Support configuring strict ssl and proxy via .apmrc file