Minor spelling fix

Very small spelling fix in the api doc
Merge pull request #424 from nachouve/patch-1

Minor spelling fix
Update installation.rst

USERENA_SIGNIN_REDIRECT_URL instead of LOGIN_REDIRECT_URL
Merge pull request #427 from Ethno-urban/patch-1

Update installation.rst
Merge remote-tracking branch 'upstream/master'
if profile instance create in signal for User model, this "create" will fail with IntegrityError