Update ngx_http_auth_ldap_module.c

added a rebind as privileged user in the same function as the user bind to reset the connextion to a usable state
updated README
Fix authentication for user/group validations

This fixes issue #40.  User passwords should *always* be checked during authentication (except when a user fails to satisfy given requirements).  Previously, the PHASE_CHECK_BIND step of authentication would not check passwords in any LDAP configuration where ``require valid_user`` was not specified (eg using ``require user`` or ``require group``).
Merge pull request #37 from prune998/patch-1

Update ngx_http_auth_ldap_module.c
Merge pull request #41 from davidjb/master

Fix authentication for user/group validations - passwords fail to be checked
Merge pull request #39 from pmenglund/readme

updated README
Merge remote-tracking branch 'upstream/master'

i.e. bring nyoxi's branch back up to current
Fix type issue in ngx_http_auth_ldap_ssl_handshake