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/.
resize big images in upload and tags implementation
Merge branch 'live' of github.com:mygetlist/pin into live
Merge pull request #85 from camilotorresf/fixes

Case insensitive profile (and email)
Admin users database sort and paginate

In the admin, the users database page now allows sort clicking on the table header.
Also supports pagination.
Admin: adds a tab for data loaders

In the search for users and in the all users in the admin, a new tab for Data Loaders is added with sort and pagination.
Refactor code

Use a mixin for fixing the date creation column in users search and dataloaders search results.
Merge pull request #86 from camilotorresf/fixes

Users database page with pagination and sorting
fetched images with user-agent header to bypass robot
Merge branch 'live' of github.com:mygetlist/pin into live
Merge pull request #87 from bimalbiswal123/live

big image fix, fix issue downloading images from url, added tags etc
merge