Added emails & username validation on profile contacts editing page (/settings/email), refs #315
After CR fixes, refs #315. Switched view to render error messages on the page, instead of just returning a string
Refs # 317 Implement API method and use it on website for email confirmation check
- implemented API method which checks username or email
- switched UsernameOrEmailValidator to API method above

 prepared API function to test username and
Merge branch 'live' of github.com:OlegYarosh/pin into edit_emails_validation

Conflicts:
	api/views/profile.py
	api_server.py