LDAP authentication via email address

Add possibility to compare the password for Owncloud instances relying
on the user_ldap app. For this to work, the User Login Filter needs to
be set to also accept login via email.
Merge branch 'master' into ldap_user_auth
DB: Increase username length

Double username column length from 32 to 64 characters. Increase version
number to 1.1.1 to trigger database schema update.
Refactoring
Add LDAP info to README
Merge pull request #26 from owncloud/ldap_user_auth

Add support for LDAP user authentication