Updated app.urls to handle new username format (with special chars)
Removed @ from app.url user urls patterns
Updated username validation patterns -> removed @ and + from accepted chars
Bump to v1.7.3
Merge branch 'hotfix/signup-unallowed-chars'
Prevent creation of "self-loop" edges #553
Bump to v1.7.4
Merge branch 'hotfix/disable-self-loop-relationship' into develop

Conflicts:
	README.md
	bower.json
	docs/conf.py
	package.json