Taiga-contrib-ldap-auth-ext

Several bug fixes to secure LDAP bind:
- always use UTF-8 for decoding values
- filter and control attributes received from LDAP

Retrieval of [Martijn Bastiaan's improvements](https://github.com/Technariumas/taiga-contrib-ldap-auth/pull/1), allowing fallback to normal login if LDAP fails.

Regrouped almost all different forks into this one, added some enhancements of my own, changed module name and uploaded stable version to pypi.

Includes:
- [Allow dot (and perhaps other characters) in username](https://github.com/ensky/taiga-contrib-ldap-auth/pull/43)
- [connector: remove duplicate SIMPLE and SYNC imports](https://github.com/ensky/taiga-contrib-ldap-auth/pull/44)
- [services: update user's DB entry from LDAP (if needed)](https://github.com/ensky/taiga-contrib-ldap-auth/pull/46)
- [Search for LDAP entry by both username and e-mail + large refactor](https://github.com/ensky/taiga-contrib-ldap-auth/pull/47)
- [support of alternative LDAP ciphersuites](https://github.com/ensky/taiga-contrib-ldap-auth/pull/53)
- [Fixed UTF-8 encoded DN](https://github.com/ensky/taiga-contrib-ldap-auth/pull/55)
- [update notes](https://github.com/ensky/taiga-contrib-ldap-auth/pull/56)
- Completion of support of alternative LDAP ciphersuites
- LDAP over START TLS
- New error message if several matches on login