Use lower case letters for username

When registering use lower case letters to store the username and the email, to have a canonical way to detect duplicated username and email.
Register username and email in lower case for facebook

When registering with facebook, use lower case username and password.
Register username and email in lower case for google
Profile URL is case insensitive

The profile URL that contains the username is now case insensitive so no matter how you write it regarding case you will always have the same profile and no error page.
Fix displaying duplicate pins

The same pin sometimes appeared duplicated in the listing for /admin/input/.
Merge pull request #85 from camilotorresf/fixes

Case insensitive profile (and email)