Feature/domain agnosticism

Some domains are vanity urls and hardcoding the EGNYTE_DOMAIN as a global precludes them from working. I added a small parse to see if we pass in a full url or just a subdomain meant to be prepended to .egnyte.com.

1. We need a function to generate a url. 
2. /v2/users and /v1/perms/user should be a constant